At the end of the 11th century, the growing settlement in the valley was walled, though settlement continued outside the wall. As the town spread up the west slopes surrounding the Birsig river, that section was walled also. At the beginning of the 13th century, all these sections were included within a single wall that embraced both the valley and hill settlements. In 1362, the city began building a new, wider city wall, which also enclosed the suburbs. It is possible that the destruction wrought by the earthquake of 1356 contributed to the decision to build a new wall. Among the construction materials were debris from the destruction and Jewish gravestones from the cemetery of the first Jewish community of Basel, which was destroyed in the violence surrounding the outbreak of the Black Death in 1348. The construction of the outer city walls was completed in 1398 and these walls lasted until the mid-nineteenth century.