Under the Normans, Norwich emerged as the hub of the region. With steady growth and strong overseas links it became an important mediaeval city, but it suffered from internal tensions, unsanitary conditions and disastrous fires. Mediaeval Norfolk was the mostly densely populated and the most productive agricultural region in the country. Land was cultivated intensively and the wool trade was sustained by huge flocks. Other industries such as peat extraction were important. Norfolk was a prosperous county and possessed a wealth of monastic establishments and parish churches.