sentences:  The period of the early Middle Ages was marked by an intensification of habitation, particularly in the areas along river valleys.The settlements were centred around the stronghold on Old Town Hill, which was likely one of the main centres of Lendians tribe.When the tribal stronghold was destroyed in the 10th century, the centre shifted to the northeast, to a new stronghold above Czechówka valley and, after the mid-12th century, to Castle Hill.