Is it permissible to marry a religious young man approved by the mother and some family members, while the guardian (brother), maternal uncle, and grandmother reject him because he is from another tribe, and would that be considered bringing shame upon the family?

There is no justification for the stance of the maternal uncle and grandmother if the suitor is a man of religion and good character. However, it is not wise to confront their obstinacy with obstinacy, as that could lead to significant problems for you and your mother. The best approach is to try and persuade the maternal uncle and brother to agree. If they agree, then praise be to Allah. If they do not agree, it is not advisable to enter into problems that you may not be able to bear, unless you are advancing in age and feel that waiting would be difficult for you, and your mother is prepared to bear the consequences of the marriage.