sentences:  Following his departure, the native princes destroyed the towns he had built in the highlands, and although in 781 they affirmed loyalty to the Caliphate, in 782 they launched a general anti-Muslim revolt that was not suppressed until 785, when Sa'id al-Harashi led 40,000 troops into the region.Relations with the caliphal governors in the lowlands improved thereafter, but the Bavandid and Karenid princes remained united in their opposition to Muslim penetration of the highlands, to the extent that they prohibited even the burial of Muslims there.Isolated acts of defiance like the murder of a tax collector occurred, but when the two princes were summoned before Harun al-Rashid in 805 they promised loyalty and the payment of a tax, and were forced to leave their sons behind as hostages for four years.