Judaic monotheism had deeply penetrated Arabia for almost a century before Muhammad declared his revelation in 610 in one of the towns - Makka, or Mecca - in which those Himyarite emigrants had settled. It was precisely because Arabian monotheism (as distinct from the confusing three-in-one version preached by Christianity) had such a strongly Judaic colouring - was in effect Arab Judaism - that Muhammad, who had lived among Jews all his life, could assume at the very least a sympathetic hearing among them, even that they might be the most receptive of the population to his prophecy, not least the part about Islam being the true Abrahamic faith.