Roman commerce in the context of "Crisis of the Third Century"

The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. Although the term is primarily used for Rome's pre-Julian calendars, it is often used inclusively of the Julian calendar established by Julius Caesar in 46 BC.

According to most Roman accounts, their original calendar was established by their legendary first king Romulus. It consisted of ten months, beginning in spring with March and leaving winter as an unassigned span of days before the next year. These months each had 30 or 31 days and ran for 38 nundinal cycles, each forming a kind of eight-day week—nine days counted inclusively in the Roman manner—and ending with religious rituals and a public market. This fixed calendar bore traces of its origin as an observational lunar one. In particular, the most important days of each month—its kalends, nones, and ides—seem to have derived from the new moon, the first-quarter moon, and the full moon respectively. To a late date, the College of Pontiffs formally proclaimed each of these days on the Capitoline Hill and Roman dating counted down inclusively towards the next such day in any month. (For example, the year-end festival of Terminalia on 23 February was called VII. Kal. Mart., the 6th day before the March kalends.)

Roman roads (Latin: viae Romanae [ˈwiae̯ roːˈmaːnae̯]; singular: via Romana [ˈwia roːˈmaːna]; meaning "Roman way") were physical infrastructure vital to the maintenance and development of the Roman state, built from about 300 BC through the expansion and consolidation of the Roman Republic and, later, the Roman Empire. They provided efficient means for the overland movement of armies, officials, civilians, inland carriage of official communications, and trade goods. Roman roads were of several kinds, ranging from small local roads to broad, long-distance highways built to connect cities, major towns and military bases. These major roads were often stone-paved and metaled, cambered for drainage, and were flanked by footpaths, bridleways and drainage ditches. They were laid along accurately surveyed courses, and some were cut through hills or conducted over rivers and ravines on bridgework. Sections could be supported over marshy ground on rafted or piled foundations.

At the peak of Rome's development, no fewer than 29 great military highways radiated from the capital, and the empire's 113 provinces were interconnected by 372 great roads. The whole comprised more than 400,000 kilometres (250,000 miles) of roads, of which over 80,500 kilometres (50,000 mi) were stone-paved. In Gaul alone, no less than 21,000 kilometres (13,000 mi) of roadways are said to have been improved, and in Britain at least 4,000 kilometres (2,500 mi). The courses (and sometimes the surfaces) of many Roman roads survived for millennia; some are overlaid by modern roads.

The Periplus of the Erythraean Sea (Koine Greek: Περίπλους τῆς Ἐρυθρᾶς Θαλάσσης, romanized: Períplous tē̂s Erythrâs Thalássēs), also known by its Latin name as the Periplus Maris Erythraei, is a Greco-Roman periplus written in Koine Greek that describes navigation and trading opportunities from Roman Egyptian ports like Berenice Troglodytica along the coast of the Red Sea and others along the Horn of Africa, the Persian Gulf, Arabian Sea and the Indian Ocean, including the modern-day Sindh region of Pakistan and southwestern regions of India.

The text has been ascribed to different dates between the first and third centuries, but a mid-first-century date is now the most commonly accepted. While the author is unknown, it is a first-hand description by someone familiar with the area and is nearly unique in providing accurate insights into what the ancient Hellenic world knew about the lands around the Indian Ocean.