Answer:
#1 The tribe of Reuben apparently settled east of the Dead Sea in the same general area occupied by the tribe of Gad and played a secondary role in the history of the Jewish people.
#2 Reuben | Hebrew tribe | Britannica.
#3 In 930 bc the 10 tribes formed the independent Kingdom of Israel in the north and the two other tribes, Judah and Benjamin, set up the Kingdom of Judah in the south.
#4 Although Jerusalem was in the territory allocated to the tribe of Benjamin (Joshua 18:28), it remained under the independent control of the Jebusites. Judges 1:21 points to the city being within the territory of Benjamin, while Joshua 15:63 implies that the city was within the territory of Judah.
#5 The tribe of Judah settled in the region south of Jerusalem and in time became the most powerful and most important tribe. Not only did it produce the great kings David and Solomon but also, it was prophesied, the Messiah would come from among its members.
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