The current Maltese people, characterised by the use of the Maltese language and by Roman Catholicism, are the descendants – through much mixing and hybridisation – of colonists from Sicily and Calabria who repopulated the Maltese islands in the beginning of the second millennium after a two-century lapse of depopulation that followed the Arab conquest by the Aghlabids in AD 870.
A genetic study by Capelli et al. indicates that Malta was barely inhabited at the turn of the tenth century and was likely to have been repopulated by settlers from Sicily and Calabria who spoke Siculo-Arabic.
Previous inhabitants of the islands – Phoenicians, Romans, Byzantines – did not leave many traces, as most nameplaces were lost and replaced.
The Normans conquered the island in 1091 and completely re-Christianised them by 1249. This re-Christianisation created the conditions for the evolution of the Maltese language from the now extinct Siculo-Arabic dialect.
The influences on the population after this have been fiercely debated among historians and geneticists. The origins question is complicated by numerous factors, including Malta's turbulent history of invasions and conquests, with long periods of depopulation followed by periods of immigration to Malta and intermarriage with the Maltese by foreigners from the Mediterranean, Western and Southern European countries that ruled Malta. The many demographic influences on the island include:
- The exile to Malta of the entire male population of the town of Celano (Italy) in 1223
- The stationing of Swabian and Sicilian Italian troops on Malta in 1240
- The removal of all remaining Arabs from Malta in 1224
- The arrival of several thousands Aragonese (i.e. Catalans, Valencians, Majorcans and proper Aragonese, from current Spain) soldiers in 1283 to 1425.
- Further waves of European repopulation throughout the 13th century
- The settlement in Malta of noble families from Sicily (Italy) and the Crown of Aragon (now mostly part of Spain) between 1372 and 1450
- The arrival of several thousand Greek Rhodian sailors, soldiers and slaves with the Knights of St. John
- The introduction of several thousand Sicilian laborers in 1551 and again in 1566
- The emigration of some 891 Italian exiles to Malta during the Risorgimento in 1849
- The posting of some 22,000 British servicemen in Malta from 1807 to 1979 (only a small number of whom remained in the islands), as well as other British and Irish who settled in Malta over the decades
- The mass emigration occurring after World War II and well into the 1960s and 70s. Many Maltese left the island for the United Kingdom, Australia, Canada and the USA. Following Malta's accession to the EU in 2004 expatriate communities grew in European countries such as the one in Belgium.
Over time, the various rulers of Malta published their own view of the ethnicity of the population. The Knights of Malta downplayed the role of Islam in Malta and promoted the idea of a continuous Roman Catholic presence,.