Mohammed, the prophet of Islam, lived in Saudia Arabia, mainly in Mecca and (later) Medina. He lived from 570-632CE. According to this wikipedia article there were Jews in Saudia Arabia at that time: ...
In a recent conversation a friend indicated that Rav Hai Gaon was a well known kabbalist, while another friend pointed to his teshuva [teshuvas ha'geonim 115] to indicate that he was not [and ...
The Mishna in M’nachot 4:1 says that the mitzvah of the white tzizit is not gone if there is no techelet, and the mitzvah of the techelet is not gone if there is no white. That seems a straight ...