I know there are two prisons in Lhasa, one for political prisoners and prisoners with long sentences, and the other for prisoners with short sentences. I know that's all. I wonder if I can help you. You can write to No.6 Zaji Road, Lhasa, Tibet, and write your brother's name. See if you can send it. I don't know the address of the second prison! I wonder if I can help you!