This African country can be divided along population lines between north and south: the north is Arab and Berber and the south are black African peoples. Over a period of 600 years, the southern part of Mauritania belonged to the kingdoms of Ghana, then Mali, and finally Sanghay. In the early 1400s the Portuguese arrived to trade. Their dominance in the area was unchallenged for the next one hundred years when the British, French, and Dutch each contested Portuguese control. The French made the region a protectorate in 1903 and a colony in 1920, granting self-government in 1958. Independence followed in 1960. In 1978, the government was overturned in a military coup but in 1984, this government was also ousted in a military coup led by the Chief of Staff. In 1985 and 1986, elections were held on the local and regional level. By 1991, a new constitution had been approved and multiparty elections held. Elections were also held in 1992 and 1997. Border clashes with Senegal as well as racial and religious conflicts have made it a difficult challenge to grow the economy.