Yemen has long existed at the crossroads of cultures, linked to some of the oldest centres of civilization in the Near East by virtue of its location in South Arabia. Between the 12th century BCE and the 6th century, it was part of the Minaean, Sabaean, Hadhramaut, Qataban, Ausan and Himyarite kingdoms, which controlled the lucrative spice trade, and later came under Ethiopian and Persian rule. In the 6th century, the Himyarite king Abu-Karib Assad converted to Judaism. In the 7th century, Islamic caliphs began to exert control over the area. After this caliphate broke up, South Arabia came under the control of many dynasties who ruled part, or often all of South Arabia. Imams of Persian origin ruled Yemen intermittently for 160 years, establishing a theocratic political structure that survived until modern times.
Egyptian Sunni caliphs occupied much of Yemen throughout the 11th century. By the 16th century and again in the 19th century, Yemen was part of the Ottoman Empire, and in some periods Imams exerted control over all of Yemen.
The modern history of south Arabia and Yemen began in 1918 when Yemen gained independence from the Ottoman Empire. Between 1918 and 1962, Yemen was a monarchy ruled by the Hamidaddin family. North Yemen then became a republic in 1962, but it was not until 1967 that the British Empire, which had set up a protective area around the South Arabia port of Aden in the 19th century, withdrew from what became South Yemen. In 1970, the southern government adopted a nominally Communist governmental system. The two countries were formally united as the Republic of Yemen on 22 May 1990.
Unfortunately, things eventually took a turn for the worse for the unified country. The USS Cole, a visiting U.S. Navy ship, was attacked by Al Qaeda in 2000 while on a fuel stop in Aden. Al Qaeda in the Arabian Peninsula has since grown stronger in the country, and the U.S. has responded by striking targets in Yemen repeatedly with drone-fired missiles. The government of longtime dictator, Ali Abdullah Saleh, fell amid dramatic protests associated with the Arab Spring in 2012, but his successor, former Vice President Abd Rabbu Mansour Hadi, hardly rushed to institute the reforms demanded by the demonstrators and was overthrown by the militia of the Shi'a Houthis, who took over the government outright in February 2015. Sunni Arab governments, especially that of Saudi Arabia, were close to Saleh and Hadi and oppose Shi'a rule in this Arabian country. They have supported a coalition of Sunni Islamists called Al-Islah in a civil war against the Houthi forces, and have led a brutal bombing campaign that has damaged the country's infrastructure to the extent that the December 14, 2014 U.S. State Department travel warning states that:
"The military conflict has significantly destroyed infrastructure, limiting the availability of electricity, clean water, and medical care, and causing travel by internal roads to be dangerous. This instability often hampers the ability of humanitarian organizations to deliver critically needed food, medicine, and water."