Swaziland, officially the Kingdom of Swaziland, is a sovereign state in Southern Africa. It is neighboured by Mozambique to its east and by South Africa to its north, west and south. The country and its people take their names from Mswati II, the 19th-century king under whose rule Swazi territory was expanded and unified. At no more than 200 kilometres (120 mi) north to south and 130 kilometres (81 mi) east to west, Swaziland is one of the smallest countries in Africa. Despite its size, however, its climate and topography is diverse, ranging from a cool and mountainous highveld to a hot and dry lowveld. The population is primarily ethnic Swazis whose language is siSwati. The country is an absolute monarchy, currently ruled by Ngwenyama (“King") Mswati III. He is head of state and appoints the country's prime ministers and a number of representatives of both chambers (Senate and House of Assembly) in the country's parliament. Swaziland is a developing country with a small economy. The Swazi population faces major health issues: HIV/AIDS and, to a lesser extent, tuberculosis are serious challenges.