Already in the mid-9th century, on the Tarnów's St. Martin Mount (Góra sw. Marcina, 2.5 kilometers from the centre of today's city), a Slavic gord was established, probably by the Vistulans. Due to efforts of local archaeologists, we know that the size of the gord was almost 16 hectares, and it was surrounded by a rampart. The settlement was probably destroyed in the 1030s or the 1050s, during either a popular rebellion against Christianity (see Baptism of Poland), or Czech invasion of Lesser Poland. In the mid-11th century, a new gord was established on the Biała river. It was a royal property, which in the late 11th or early 12th century was handed over to the Tyniec Benedictine Abbey. The name Tarnów, with a different spelling, was for the first time mentioned in a document of Papal legate, Cardinal Gilles de Paris (1124).