Complex sentence: The first European to encounter the Mekong was the Portuguese Antonio de Faria in 1540; a European map of 1563 depicts the river, although even by then little was known of the river upstream of the delta.
Split into simpler sentences: The first European to encounter the Mekong was the Portuguese Antonio de Faria in 1540. A European map of 1563 depicts the river, although even by then little was known of the river upstream of the delta.