effects of PCB pollution. History Evidence of the first human habitation of the area by Neanderthals dates back to 125,000 years ago. It is believed that the Rock of Gibraltar may have been one of the last outposts of Neanderthal habitation in the world, with evidence of their presence there dating to as recently as 24,000 years ago. Archaeological evidence of Homo sapiens habitation of the area dates back years. The relatively short distance between the two shores has served as a quick crossing point for various groups and civilizations throughout history, including Carthaginians campaigning against Rome, Romans travelling between the provinces of Hispania and Mauritania, Vandals raiding south from Germania through Western Rome and into North Africa in the 5th century, Moors and Berbers in the 8th–11th centuries, and Spain and Portugal in the 16th century. Beginning in 1492, the Strait began to play a certain cultural role in acting as a barrier against cross-channel conquest and the flow of culture and language that would naturally follow such a conquest. In that year, the last Muslim government north of the Strait was overthrown by a Spanish force. Since that time, the Strait has come to foster the development of two very distinct and varied cultures on either side of it after sharing much the same culture for over 500 years from the 8th century to the early 13th century. On the northern side, Christian-European culture has remained dominant since the expulsion of the last Muslim kingdom in 1492, along with the Romance Spanish language, while on the southern side, Muslim-Arabic/Mediterranean has been dominant since the spread of Islam into North Africa in the 700s, along with the Arabic language. For the last 500 years, religious and cultural intolerance, more than the small travel barrier that the Strait presents, has come to act as a powerful enforcing agent of the cultural separation that exists between these two groups. The small British enclave of the city of Gibraltar presents a third cultural group found in the Strait. This enclave was first established in 1704 and has since been used by Britain to act as a surety for control of the sea lanes into and out of the Mediterranean. Following the Spanish coup of July 1936 the Spanish Republican Navy tried to blockade the Strait of Gibraltar to hamper the transport of Army of Africa troops from Spanish Morocco to Peninsular Spain.