Flint tools found in the Maastricht area have been estimated to be 250,000 years old. The first definable culture (c. 3000 BC) was the Late Stone Age ‘Funnel-neck Beaker’ culture, named after the objects made by a people known for their monolithic burial monuments. The environment of the ‘Low Countries’ affected the behaviour of its earliest inhabitants, as demonstrated by the terpen—islands of earth and clay—built by the autochthonous Frisians (Frisii) c. 500 BC as protection from the sea.