Yemen, officially the Republic of Yemen, is a country in Western Asia, on the southern end of the Arabian Peninsula. It borders Saudi Arabia to the north and Oman to the northeast and shares maritime borders with Eritrea, Djibouti, and Somalia. It is the second-largest Arab sovereign state in the peninsula, occupying 555,000 square kilometres. The coastline stretches for about 2,000 kilometres. Yemen's constitutionally stated capital, and largest city, is the city of Sanaa, but the city has been under Houthi rebel control since February 2015 as well as Aden, which is also controlled by the Southern Transitional Council since 2018. Its executive administration resides in Riyadh, Saudi Arabia.
In ancient times, Yemen was the home of the Sabaeans, a trading state that included parts of modern-day Ethiopia and Eritrea. In 275 CE, later the Jewish-influenced Himyarite Kingdom. Christianity arrived in the fourth century. Islam spread quickly in the seventh century and Yemenite troops were crucial in the early Islamic conquests. Several dynasties emerged in the 9th to 16th centuries, such as the Rasulid dynasty.