Proto-language in the context of Language convergence

South Asia is the southern subregion of Asia that is defined in both geographical and ethnic-cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's population. As commonly conceptualised, the modern states of South Asia include Bangladesh, Bhutan, India, the Maldives, Nepal, Pakistan, and Sri Lanka, with Afghanistan also often included, which may otherwise be classified as part of Central Asia. South Asia borders East Asia to the northeast, Central Asia to the northwest, West Asia to the west and Southeast Asia to the east. Apart from Southeast Asia, Maritime South Asia is the only subregion of Asia that lies partly within the Southern Hemisphere. The British Indian Ocean Territory and two out of 26 atolls of the Maldives in South Asia lie entirely within the Southern Hemisphere. Topographically, it is dominated by the Indian subcontinent and is bounded by the Indian Ocean in the south, and the Himalayas, Karakoram, and Pamir Mountains in the north.

Settled life emerged on the Indian subcontinent in the western margins of the Indus River Basin 9,000 years ago, evolving gradually into the Indus Valley Civilisation of the third millennium BCE. By 1200 BCE, an archaic form of Sanskrit, an Indo-European language, had diffused into India from the northwest, with the Dravidian languages being supplanted in the northern and western regions. By 400 BCE, stratification and exclusion by caste had emerged within Hinduism, and Buddhism and Jainism had arisen, proclaiming social orders unlinked to heredity.

A language family is a group of languages related through descent from a common ancestor, called the proto-language of that family. The term family is a metaphor borrowed from biology, with the tree model used in historical linguistics analogous to a family tree, or to phylogenetic trees of taxa used in evolutionary taxonomy. Linguists thus describe the daughter languages within a language family as being genetically related. The divergence of a proto-language into daughter languages typically occurs through geographical separation, with different regional dialects of the proto-language undergoing different language changes and thus becoming distinct languages over time.

One well-known example of a language family is the Romance languages, including Spanish, French, Italian, Portuguese, Romanian, Catalan, Romansh, and many others, all of which are descended from Vulgar Latin. The Romance family itself is part of the larger Indo-European family, which includes many other languages native to Europe and South Asia, all believed to have descended from a common ancestor known as Proto-Indo-European.

India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area; the most populous country since 2023; and, since its independence in 1947, the world's most populous democracy. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west; China, Nepal, and Bhutan to the north; and Bangladesh and Myanmar to the east. In the Indian Ocean, India is near Sri Lanka and the Maldives; its Andaman and Nicobar Islands share a maritime border with Myanmar, Thailand, and Indonesia.

Modern humans arrived on the Indian subcontinent from Africa no later than 55,000 years ago. Their long occupation, predominantly in isolation as hunter-gatherers, has made the region highly diverse. Settled life emerged on the subcontinent in the western margins of the Indus river basin 9,000 years ago, evolving gradually into the Indus Valley Civilisation of the third millennium BCE. By 1200 BCE, an archaic form of Sanskrit, an Indo-European language, had diffused into India from the northwest. Its hymns recorded the early dawnings of Hinduism in India. India's pre-existing Dravidian languages were supplanted in the northern regions. By 400 BCE, caste had emerged within Hinduism, and Buddhism and Jainism had arisen, proclaiming social orders unlinked to heredity. Early political consolidations gave rise to the loose-knit Maurya and Gupta Empires. Widespread creativity suffused this era, but the status of women declined, and untouchability became an organised belief. In South India, the Middle kingdoms exported Dravidian language scripts and religious cultures to the kingdoms of Southeast Asia.

A root (also known as a root word or radical) is the core of a word that is irreducible into more meaningful elements. In morphology, a root is a morphologically simple unit which can be left bare or to which a prefix or a suffix can attach. The root word is the primary lexical unit of a word, and of a word family (this root is then called the base word), which carries aspects of semantic content and cannot be reduced into smaller constituents.Content words in nearly all languages contain, and may consist only of, root morphemes. However, sometimes the term "root" is also used to describe the word without its inflectional endings, but with its lexical endings in place. For example, chatters has the inflectional root or lemma chatter, but the lexical root chat. Inflectional roots are often called stems. A root, or a root morpheme, in the stricter sense, is a mono-morphemic stem. An etymon is the root word in a proto-language from which the descendant forms arose.

The traditional definition allows roots to be either free morphemes or bound morphemes. Root morphemes are the building blocks for affixation and compounds. However, in polysynthetic languages with very high levels of inflectional morphology, the term "root" is generally synonymous with "free morpheme". Many languages have a very restricted number of morphemes that can stand alone as a word: Yup'ik, for instance, has no more than two thousand.

Proto-Slavic (abbreviated PSl., PS.; also called Common Slavic or Common Slavonic) is the unattested, reconstructed proto-language of all Slavic languages. It represents Slavic speech approximately from the 2nd millennium BC through the 6th century AD. As with most other proto-languages, no attested writings have been found; scholars have reconstructed the language by applying the comparative method to all the attested Slavic languages and by taking into account other Indo-European languages.

Rapid development of Slavic speech occurred during the Proto-Slavic period, coinciding with the massive expansion of the Slavic-speaking area. Dialectal differentiation occurred early on during this period, but overall linguistic unity and mutual intelligibility continued for several centuries, into the 10th century or later. During this period, many sound changes diffused across the entire area, often uniformly. This makes it inconvenient to maintain the traditional definition of a proto-language as the latest reconstructable common ancestor of a language group, with no dialectal differentiation. (This would necessitate treating all pan-Slavic changes after the 6th century or so as part of the separate histories of the various daughter languages.) Instead, Slavicists typically handle the entire period of dialectally differentiated linguistic unity as Common Slavic.

Proto-Celtic, or Common Celtic, is the reconstructed ancestral proto-language of all known Celtic languages, and a descendant of Proto-Indo-European. It is not attested in writing but has been partly reconstructed through the comparative method. Proto-Celtic is generally thought to have been spoken between 1300 and 800 BC, after which it began to split into different languages. Proto-Celtic is often associated with the Urnfield culture and particularly with the Hallstatt culture. Celtic languages share common features with Italic languages that are not found in other branches of Indo-European, suggesting the possibility of an earlier Italo-Celtic linguistic unity.

Proto-Celtic is currently being reconstructed through the comparative method by relying on later Celtic languages. Though Continental Celtic presents much substantiation for Proto-Celtic phonology, and some for its morphology, recorded material is too scanty to allow a secure reconstruction of syntax, though some complete sentences are recorded in the Continental Gaulish and Celtiberian. So, the main sources for reconstruction come from Insular Celtic languages with the oldest literature found in Old Irish and Middle Welsh, dating back to authors flourishing in the 6th century AD.

The Slavic languages, also known as the Slavonic languages, are Indo-European languages spoken primarily by the Slavic peoples and their descendants. They are thought to descend from a proto-language called Proto-Slavic, spoken during the Early Middle Ages, which in turn is thought to have descended from the earlier Proto-Balto-Slavic language, linking the Slavic languages to the Baltic languages in a Balto-Slavic group within the Indo-European family.

The current geographical distribution of natively spoken Slavic languages includes the Balkans, Central and Eastern Europe, and all the way from Western Siberia to the Russian Far East. Furthermore, the diasporas of many Slavic peoples have established isolated minorities of speakers of their languages all over the world. The number of speakers of all Slavic languages together was estimated to be 315 million at the turn of the twenty-first century. It is the largest and most diverse ethno-linguistic group in Europe.

Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. No direct record of Proto-Indo-European has been discovered; its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. Far more work has gone into reconstructing PIE than any other proto-language, and it is the best understood of all proto-languages of its age. The majority of linguistic work during the 19th century was devoted to the reconstruction of PIE and its daughter languages, and many of the modern techniques of linguistic reconstruction (such as the comparative method) were developed as a result.

PIE is hypothesized to have been spoken as a single language from approximately 4500 BCE to 2500 BCE during the Late Neolithic to Early Bronze Age, though estimates vary by more than a thousand years. According to the prevailing Kurgan hypothesis, the original homeland of the Proto-Indo-Europeans may have been in the Pontic–Caspian steppe of eastern Europe. The linguistic reconstruction of PIE has provided insight into the pastoral culture and patriarchal religion of its speakers. As speakers of Proto-Indo-European became isolated from each other through the Indo-European migrations, the regional dialects of Proto-Indo-European spoken by the various groups diverged, as each dialect underwent shifts in pronunciation (the Indo-European sound laws), morphology, and vocabulary. Over many centuries, these dialects transformed into the known ancient Indo-European languages. From there, further linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages.

In linguistics, the comparative method is a technique for studying the development of languages by performing a feature-by-feature comparison of two or more languages with common descent from a shared ancestor and then extrapolating backwards to infer the properties of that ancestor. The comparative method may be contrasted with the method of internal reconstruction in which the internal development of a single language is inferred by the analysis of features within that language. Ordinarily, both methods are used together to reconstruct prehistoric phases of languages; to fill in gaps in the historical record of a language; to discover the development of phonological, morphological and other linguistic systems and to confirm or to refute hypothesised relationships between languages.

The comparative method emerged in the early 19th century with the birth of Indo-European studies, then took a definite scientific approach with the works of the Neogrammarians in the late 19th–early 20th century. Key contributions were made by the Danish scholars Rasmus Rask (1787–1832) and Karl Verner (1846–1896), and the German scholar Jacob Grimm (1785–1863). The first linguist to offer reconstructed forms from a proto-language was August Schleicher (1821–1868) in his Compendium der vergleichenden Grammatik der indogermanischen Sprachen, originally published in 1861. Here is Schleicher's explanation of why he offered reconstructed forms:

Pontic is a proposed language family or macrofamily, comprising the Indo-European and Northwest Caucasian language families, with Proto-Pontic being its reconstructed proto-language.

In historical linguistics, the tree model (also Stammbaum, genetic, or cladistic model) is a model of the evolution of languages analogous to the concept of a family tree, particularly a phylogenetic tree in the biological evolution of species. As with species, each language is assumed to have evolved from a single parent or "mother" language, with languages that share a common ancestor belonging to the same language family.

Popularized by the German linguist August Schleicher in 1853, the tree model has been a common method of describing genetic relationships between languages since the first attempts to do so. It is central to the field of comparative linguistics, which involves using evidence from known languages and observed rules of language feature evolution to identify and describe the hypothetical proto-languages ancestral to each language family, such as Proto-Indo-European and the Indo-European languages. However, this is largely a theoretical, qualitative pursuit, and linguists have always emphasized the inherent limitations of the tree model due to the large role played by horizontal transmission in language evolution, ranging from loanwords to creole languages that have multiple mother languages. The wave model was developed in 1872 by Schleicher's student Johannes Schmidt as an alternative to the tree model that incorporates horizontal transmission.

Proto-Iranian or Proto-Iranic is the reconstructed proto-language of the Iranian languages branch of Indo-European language family and thus the ancestor of the Iranian languages such as Persian, Pashto, Sogdian, Zazaki, Ossetian, Mazandarani, Kurdish, Talysh and others. Its speakers, the hypothetical Proto-Iranians, are assumed to have lived in the 2nd millennium BC and are usually connected with the Andronovo archaeological horizon (see Indo-Iranians).

Proto-Iranian was a satem language descended from the Proto-Indo-Iranian language, which in turn, came from the Proto-Indo-European language. It was likely removed less than a millennium from the Avestan language, and less than two millennia from Proto-Indo-European.

Comparative linguistics is a branch of historical linguistics that is concerned with comparing languages to establish their historical relatedness.

Genetic relatedness implies a common origin or proto-language and comparative linguistics aims to construct language families, to reconstruct proto-languages and specify the changes that have resulted in the documented languages. To maintain a clear distinction between attested and reconstructed forms, comparative linguists prefix an asterisk to any form that is not found in surviving texts. A number of methods for carrying out language classification have been developed, ranging from simple inspection to computerised hypothesis testing. Such methods have gone through a long process of development.

Japonic or Japanese–Ryukyuan (Japanese: 日琉語族, romanized: Nichiryū gozoku) is a language family comprising Japanese, spoken in the main islands of Japan, and the Ryukyuan languages, spoken in the Ryukyu Islands. The family is universally accepted by linguists, and significant progress has been made in reconstructing the proto-language, Proto-Japonic. The reconstruction implies a split between all dialects of Japanese and all Ryukyuan varieties, probably before the 7th century. The Hachijō language, spoken on the Izu Islands, is also included, but its position within the family is unclear.

Most scholars believe that Japonic was brought to the Japanese archipelago from the Korean peninsula with the Yayoi culture during the 1st millennium BC. There is some fragmentary evidence suggesting that Japonic languages may still have been spoken in central and southern parts of the Korean peninsula (see Peninsular Japonic) in the early centuries AD.

In historical linguistics, the homeland or Urheimat (/ˈʊərhaɪmɑːt/ OOR-hye-maht, from German ur- 'original' and Heimat 'home') of a proto-language is the region in which it was spoken before splitting into different daughter languages. A proto-language is the reconstructed or historically attested parent language of a group of languages that are genetically related.

Depending on the age of the language family under consideration, its homeland may be known with near-certainty (in the case of historical or near-historical migrations) or it may be very uncertain (in the case of deep prehistory). Next to internal linguistic evidence, the reconstruction of a prehistoric homeland makes use of a variety of disciplines, including archaeology and archaeogenetics.

Sino-Tibetan (also referred to as Trans-Himalayan) is a family of more than 400 languages, second only to Indo-European in number of native speakers. Around 1.4 billion people speak a Sino-Tibetan language. The vast majority of these are the 1.3 billion native speakers of Sinitic languages. Other Sino-Tibetan languages with large numbers of speakers include Burmese (33 million) and the Tibetic languages (6 million). Other languages of the family are spoken in the Himalayas, the Southeast Asian Massif, and the eastern edge of the Tibetan Plateau. Most of these have small speech communities in remote mountain areas, and as such are poorly documented.

Several low-level subgroups have been securely reconstructed, but reconstruction of a proto-language for the family as a whole is still at an early stage, so the higher-level structure of Sino-Tibetan remains unclear. Although the family is traditionally presented as divided into Sinitic (i.e. Chinese languages) and Tibeto-Burman branches, a common origin of the non-Sinitic languages has never been demonstrated.