They are descended from ancient Arab Christian clans that did not convert to Islam, such as the Kahlani Qahtani tribes of Ancient history of Yemen (i.e.Ghassanids, and Banu Judham) who settled in Transjordan and Syria, as well as Arabized Christians, such as Melkites and Antiochian Greek Christians.
Arab Christians are not the only Christian group in the Middle East, with significant non-Arab indigenous Christian communities of ethnic Assyrians, Assyrian people, Armenians and others.
Although sometimes classified as "Arab Christians", the largest Middle Eastern Christian groups of Maronites and Copts often claim non-Arab ethnicity: a significant proportion of Maronites claim descent from the ancient Phoenicians while Copts also eschew an Arab identity, preferring an Ancient Egyptian one.
Arab Christians are Indigenous peoples of Western Asia, with a presence there predating the seventh-century Early Muslim conquests in the Fertile Crescent.
There were many Arab tribes which adhered to Christianity beginning with the 1st century, including the partly-Arab Nabateans (who incorporated elements of both Arabs and Arameans) Nabateans were possibly among the first Arab tribes to arrive to the Southern Levant in the very late first millennium BC.
At first, they were converted to Judaism, during the expansion campaigns of the Hasmonean dynasty at the first and second centuries BC.
However, by the fourth century Nabateans had converted to Christianity.
The new Arab invaders, who soon pressed forward into their seats found the remnants of the Nabataeans transformed into peasants.
Emigrants from Arab Christian (including Melkite) communities make up a significant proportion of the Middle Eastern diaspora, with sizable population concentrations across the Americas, most notably in Chile, Mexico, Venezuela, Colombia, Brazil and the US.
The first Arab tribes to adopt Christianity were likely Nabataeans and Ghassanids.