The Sabaeans were an Arabian people who inhabited the ancient region of Sheba in what is now Yemen from 1200 BC to 275 AD; Ma'rib was their capital. The Sabaean kingdom built dams, invented new irrigation techniques, and became experts in managing the scarce water of the dry areas of the inhospitable desert. The Sabaeans were also very good sailors, with excellent trade relations with people living across the Red Sea, as the most important source of profit and wealth in Saba was the lucrative trade of frankincense and myrrh. As a nation of traders, farmers and engineers, the Sabaeans were not natural warriors, preferring to trust mercenaries to protect their trade routes and caravans. However, they were highly-resilient, tough people who were formidable enemies of anyone daring to threaten their great capital city of Marib. Located at the southernmost part of the Arabian Peninsula, Saba had relatively secure borders to the south and west, accessible only by water. Their naval expertise allowed for them to plan expansion into Ethiopia, but they decided to preserve the good trading relations that had been established with the people to the west, focusing on becoming the dominant power in the region by achieving a full monopoly on the spice trade that passed through Sabaean territory along the Silk Road. In 275 AD, the kingdom was conquered by Himyar.