The Sabaean kingdom was located in what is now Marib in northern Yemen. The Sabaean kings made their capital at Ma'rib, and built great irrigation works such as the Ma'rib dams, whose ruins are still visible. The Marib Dam supported a flourishing culture for more than a thousand years; its collapse in 575 CE, before the birth of Muhammad, may be one of the main reasons that Arabia did not become Christian.They also built castles and temples in the area, and were known for trading the valuable frankincense and myrrh.They were a seafaring people and were known to have influence and a population in the Northeast African kingdom of Dʿmt, across the Red Sea in Eritrea and Ethiopia, the only other source of both frankincense and myrrh. (Taken from Wikipedia)