Although the first fortifications on Lisbon's Castelo hill are known to be no older than the 2nd century BC, recent archaeological finds have shown that Iron Age people occupied the site from the 8th to 6th centuries BC. This indigenous settlement maintained commercial relations with the Phoenicians, which would account for the recent findings of Phoenician pottery and other material objects. Archaeological excavations made near the Castle of São Jorge (''Castelo de São Jorge'') and Lisbon Cathedral indicate a Phoenician presence at this location since 1200 BC, and it can be stated with confidence that a Phoenician trading post stood on a site now the centre of the present city, on the southern slope of Castle hill. The sheltered harbour in the Tagus River estuary was an ideal spot for an Iberian settlement and would have provided a secure harbour for unloading and provisioning Phoenician ships. The Tagus settlement was an important centre of commercial trade with the inland tribes, providing an outlet for the valuable metals, salt and salted-fish they collected, and for the sale of the Lusitanian horses renowned in antiquity.