There are 3 views regarding this sect:
1. It is an offshoot and a sect of Hinduism. Few Hindus claim this.
2. It is a mixture of Hinduism and Islam. Most of the historians and scholars of comparative student do rely on this opinion.
3. It is a new revelation. Sikhs do appreciate this opinion.
Sikhs do not believe in the prophecy of the last prophet (pbuh) so are not considered as Muslims and on the other side are not People of Book (Jews, Christian..). As per Ayatullah Sistani only Muslims and People of Book are considered to be Tahir.