The Wawel Hill has archaeological remains indicating settlement from the 4th century. Archaeological studies suggest that the earliest settlement dates back to the Middle Paleolithic era, c. 100,000 years BC and owed its rapid development to its location being the crossing of a number of key trading routes. Wawel is believed to be one of the strongholds of the Vistulan tribe which formed a nation at the turn of the 8th and 9th century AD. Its legendary rulers Krakus and Princess Wanda, who are said to have lived in the 7th and 8th centuries, are mentioned by the 13th-century chronicler Wincenty Kadłubek. In the 10th century, the Vistulans’ lands and Kraków became part of the emerging state of Poland.