 Urban development began in the Po Valley much later than in southern Italy or Greece.The first known ancient inhabitants of the thick forests and swamps were the Ligurians, an Indo-European race of people.After the progressive immigration in the 7th century BC of Celtic peoples known as the Insubres (hence the name of Insubria sometimes being given to northwestern Lombardy), the southern and central regions were conquered and colonised here and there by a pre-Indo-European people, the Etruscans, who left names such as Parma, Ravenna and Felsina, the ancient name of Bologna.