Studies on extant mtDNA in Mértola, an archaeological jewel of the Islamic Period in Portugal showed a significantly higher proportion of Southern and Eastern Mediterranean lineages when compared with other general and regional Portuguese databases. This is an evidence for the movement of people through the Mediterranean basin between centres of trade, as the fluvial port of Mértola. Studies on ancient DNA were, unfortunately, inconclusive probably due to contamination due to percolation between overlapped layers of Paleo-Christian and Islamic burials in one necropolis found in Mértola.