The trend towards more permanent settlements and diversified economies continued unabated in the Iron Age and led to the development of distinct and stable regional cultures. The most characteristic of Apulian craft products, the pottery, brightly illustrates the strength and independent taste of the local culture. Traditional, conservative and selective in their use of Greek models, the Apulian potters produced types and designs largely of their own invention. Geographical proximity made it very easy for Apulian traders and craftsmen to import and often imitate the products of the Greek world. From the ninth century, there were close contacts and frequent exchanges between the Mid-Adriatic region and the Liburnian and Istrian zones across the Adriatic. The rivers that traverse the Mid-Adriatic region served as arteries of communication with Tyrrhenian Italy. The Roman tradition about the Umbri being the most ancient people of Italy becomes understandable, and the more innovatory and evolved character of their language as compared with Oscan.