In accordance with all that Moses the servant of God had commanded

1 Chronicles 6:49-81
But Aaron and his descendants were the ones who presented offerings on the altar of burnt offering and on the altar of incense in connection with all that was done in the Most Holy Place, making atonement for Israel, in accordance with all that Moses the servant of God had commanded.
So the descendants of Aaron. The total number of towns distributed among the Kohathite clans came to thirteen. 
The rest of Kohath’s descendants were allotted ten towns from the clans of half the tribe of Manasseh.
The descendants of Merari, clan by clan, were allotted twelve towns from the tribes of Reuben, Gad, and Zebulun.
Why?
Aaron and his descendants serving the Lord in the inner Tabernacle. They got town through allotted in the other 12 tribes. It is fair and under the hands of the Lord.
Aaron has 13, Kohath has 10 and Merari has 12 towns. This is the description of the Levi's descendants
All of these are in accordance with all that Moses the servant of God had commanded. This is the way of dealing with each one's portion.
祭司的工作是把人帶到神面前，不是我們能幫助他們，是神的能力。我們是君尊的祭司。
記載利未人所住的地方，而是分散在各個地方，就像今天希望每個地方都有基督徒為主發光、每個地方都有教會，每個民族都有自己語言的聖經。全國各地都有敬畏神的人住在那裏。責任上不僅是禮儀的服事，也有生活上，行為上的影響力。如今天我們所在之處，活出神的榮耀，在所在之處發揮我們的影響力，擔當人的軟弱，帶人到神面前。
How?
There is not absolute equal in the world, but there is not too much different. This is the world of the Lord.