clannish

1. ADJ If you describe a group of people as clannish, you mean that they often spend time together and may seem unfriendly to other people who are not in the group. 自成一伙且排外的[非正式]

They were a clannish lot, not given to welcoming strangers. 他们是一伙喜好扎堆的人，不太欢迎陌生人。