Penghu in the context of "Penghu Channel"

The history of the island of Taiwan dates back tens of thousands of years to the earliest known evidence of human habitation. The sudden appearance of a culture based on agriculture around 3000 BC is believed to reflect the arrival of the ancestors of today's Taiwanese indigenous peoples. People from China gradually came into contact with Taiwan by the time of the Yuan dynasty (1271–1368) and Han Chinese people started settling there by the early 17th century. The island became known by the West when Portuguese explorers discovered it in the 16th century and named it Formosa. Between 1624 and 1662, the south of the island was colonized by the Dutch headquartered in Zeelandia in present-day Anping, Tainan whilst the Spanish built an outpost in the north, which lasted until 1642 when the Spanish fortress in Keelung was seized by the Dutch. These European settlements were followed by an influx of Hoklo and Hakka immigrants from Fujian and Guangdong.

In 1662, Koxinga defeated the Dutch and established a base of operations on the island. His descendants were defeated by the Qing dynasty in 1683 and their territory in Taiwan was annexed by the Qing dynasty. Over two centuries of Qing rule, Taiwan's population increased by over two million and became majority Han Chinese due to illegal cross-strait migrations from mainland China and encroachment on Taiwanese indigenous territory. Due to the continued expansion of Chinese settlements, Qing-governed territory eventually encompassed the entire western plains and the northeast. This process accelerated in the later stages of Qing rule when settler colonization of Taiwan was actively encouraged. The Qing ceded Taiwan and Penghu to Japan after losing the First Sino-Japanese War in 1895. Taiwan experienced industrial growth and became a productive rice- and sugar-exporting Japanese colony. During the Second Sino-Japanese War it served as a base for invasions of China, and later Southeast Asia and the Pacific during World War II.

Taiwan, officially the Republic of China (ROC), is a country in East Asia. The island of Taiwan, formerly known to Westerners as Formosa, has an area of 35,808 square kilometres (13,826 sq mi) and makes up 99% of the land under ROC control. It lies about 180 kilometres (112 mi) across the Taiwan Strait from the southeastern coast of the Mainland China. The East China Sea is to the north of the island, the Philippine Sea to its east, the Luzon Strait directly to its south, and the South China Sea to its southwest. The ROC also controls a number of smaller islands, including the Penghu archipelago in the Taiwan Strait, Kinmen and Matsu in Fuchien near the Mainland coast, as well as Pratas and Taiping in the South China Sea.

Geologically, the main island comprises a tilted fault block, characterized by the contrast between the eastern two-thirds, consisting mostly of five rugged mountain ranges running parallel to the east coast, and the flat to gently rolling plains of the western third, where the majority of the population resides. Several peaks exceed 3,500 m in height – the highest, Yu Shan at 3,952 m (12,966 ft), makes Taiwan the world's fourth-highest island. The tectonic boundary that formed these ranges remains active, and the island experiences many earthquakes, some of them highly destructive. There are also many active submarine volcanoes in the Taiwan Straits.

The Taiwan Area, also called the Taiwan Area of the Republic of China, the free area of the Republic of China, and the "Tai-Min Area (Taiwan and Fuchien)", is a term used to refer to the territories under the effective control of the Republic of China (ROC, commonly known as "Taiwan"). It has been in official use since the Additional Articles of the Constitution of the Republic of China took effect, ending temporary anti-communist provisions on 1 May 1991. The term is also used in the 1992 Cross-Strait Act.

The area currently under the definition consists of the island groups of Taiwan, Penghu, Kinmen, Matsu and some minor islands. The collective term "Tai-Peng-Kin-Ma" is literally equivalent except that it only refers to the geographical areas of Taiwan, Penghu, Kinmen and Matsu Area, to the exclusion of Wuqiu, Dongsha Island, and Taiping Island.

The Treaty of Shimonoseki (Japanese: 下関条約, Hepburn: Shimonoseki Jōyaku), also known as the Treaty of Maguan in China or the Treaty of Bakan (馬關條約, Bakan Jōyaku) in Japan, was signed in Shimonoseki, Japan, on April 17, 1895, between the Empire of Japan and the Qing dynasty. The treaty ended the First Sino-Japanese War, in which the Japanese decisively defeated the Chinese land and naval forces. The treaty was signed at the Shunpanrō [ja] hotel by Count Itō Hirobumi and Viscount Mutsu Munemitsu for Japan and Li Hongzhang and his son Li Jingfang on behalf of China.

The peace conference took place from March 20 to April 17, 1895, and the treaty followed and superseded the Sino-Japanese Friendship and Trade Treaty of 1871. It consisted of 11 articles which provided for the termination of China's tributary relations with Korea; required that China pay an indemnity of 200 million taels and cede Taiwan (Formosa), the Penghu (Pescadores) Islands, and the Liaodong Peninsula to Japan; and opened four cities (Shashi, Chongqing, Suzhou, and Hangzhou) to Japan as trading ports. However, due to the diplomatic Triple Intervention of Russia, Germany, and France just one week after the treaty was signed, the Japanese withdrew their claim to the Liaodong Peninsula in return for an additional war indemnity of 30 million taels from China.

The population of Taiwan is approximately 23.36 million as of April 2025.

Immigration of Han Chinese to the Penghu Islands started as early as the 13th century. The main island was inhabited by a diversity of Taiwanese indigenous peoples speaking Austronesian languages until Han settlement began in the early 17th century, around the time of the Ming–Qing transition, when workers were mainly imported from Minnan region to the colony of Dutch Formosa in the southwest of Taiwan. According to governmental statistics, in the early 21st century, 95% to 97% of Taiwan's population are Han Taiwanese, while about 2.3% are Taiwanese of Austronesian ethnicity. Half the population are followers of one or a mixture of 25 recognized religions.

The island of Taiwan, along with the Penghu Islands, became an annexed territory of the Empire of Japan in 1895, when the Qing dynasty ceded Fujian-Taiwan Province in the Treaty of Shimonoseki after the Japanese victory in the First Sino-Japanese War. After Japanese forces crushed the consequent Republic of Formosa resistance movement, Japan ruled Taiwan for 50 years. Its capital was located in Taihoku (Taipei), the seat of the Governor-General of Taiwan.

Taiwan was Japan's first colony and can be viewed as the first step in implementing their "Southern Expansion Doctrine" of the late 19th century. Japan, which aimed to turn Taiwan into a showpiece "model colony", made efforts to improve the island's economy, public works, industry, cultural Japanization (1937 to 1945), and support the necessities of Japanese military aggression in the Asia-Pacific. Japan established monopolies and by 1945, had taken over all sales of opium, salt, camphor, tobacco, alcohol, matches, weights and measures, and petroleum on the island. Most Taiwanese children did not attend schools established by Japan until primary education was made mandatory in 1943.