The Himyarite annexed Sana’a from Hamdan around 100 CE. Hashdi tribesmen rebelled against them and regained Sana’a around 180 AD. Shammar Yahri’sh had not conquered Hadramout, Najran, and Tihama until 275 CE, thus unifying Yemen and consolidating Himyarite rule. The Himyarites rejected polytheism and adhered to a consensual form of monotheism called Rahmanism.
In 354 CE, Roman Emperor Constantius II sent an embassy headed by Theophilos the Indian to convert the Himyarites to Christianity. According to Philostorgius, the mission was resisted by local Jews. Several inscriptions have been found in Hebrew and Sabaean praising the ruling house in Jewish terms for “…helping and empowering the People of Israel.”
According to Islamic traditions, King As’ad the Perfect mounted a military expedition to support the Jews of Yathrib. Abu Kariba As’ad, as known from the inscriptions, led a military campaign to central Arabia or Najd to support the vassal Kingdom of Kindah against the Lakhmids. However, no direct reference to Judaism or Yathrib was discovered from his lengthy reign. Abu Kariba died in 445 CE, having reigned for almost 50 years. By 515 AD, Himyar became increasingly divided along religious lines and a bitter conflict between different factions paved the way for an Aksumite intervention. The last Himyarite king Ma’adikarib Ya’fur was supported by Aksum against his Jewish rivals. Ma’adikarib was Christian and launched a campaign against the Lakhmids in southern Iraq, with the support of other Arab allies of Byzantium. The Lakhmids were a Bulwark of Persia, which was intolerant to a proselytizing religion like Christianity.