The Kingdom of Kongo was formed around 1400 from a merging of the kingdoms of Mpemba Kasi & Mbata Kingdom on the left banks of the lower Congo River. Its territorial control along the river remained limited to what corresponds to the modern Bas-Congo province. European exploration of the Congo begins in 1482, when Portuguese explorer Diogo Cão discovered the river estuary (likely in August 1482), which he marked by a Padrão, or stone pillar (still existing, but only in fragments) erected on Shark Point. Cão also sailed up the river for a short distance, establishing contact with the Kingdom of Congo. The full course of the river remained unknown throughout the early modern period.