Gideon,
The Bible says nothing good about these tribes, and God did not want the Israelites to marry from these tribes either. However, during Saint Hilarion's life, the people of Palestine were Christians. From 300 to 600 AD, they were primarily a Christian nation, and then Mohammed was born. It took 100 years, but practically the entire Middle East was conquered. But even with that, not all are made for the sword, for even Adam's son Enoch could be saved and highly favoured by GOD, so can the Muslims that follow Jesus Christ as their saviour. They mourn the loss of their heritage for a bowl of soup but i think its better to be a Gentile who is unnumbered rather than the Israelites who are numbered.