Back at that time, there were not a sufficient number of Levites to care for temple service. So non - Israelite Nethinim were given more to do in helping the Levites.
لِذلِكَ أُوكِلَ إِلَى ٱلنَّثِينِيمِ غَيْرِ ٱلْإِسْرَائِيلِيِّينَ ٱلْقِيَامُ بِأَعْمَالٍ إِضَافِيَّةٍ لِمُسَاعَدَةِ ٱللَّاوِيِّينَ .‏