two hundred and twelve. These were for the Tabernacle (1Ch_9:21). In Neh_11:19, it is 172, excluding those in the villages. Not the 4,000 of 1Ch_23:5, or their ninety-three heads (1Ch 26), which were for the future Temple.
their genealogy = [Was registered] in their villages. There is no record of this. But Samuel stood at the head.
did ordain = founded Compare 1Ch_23:1-6. Compare Act_3:24.