There are many sects in Tibetan Buddhism, including the Yellow Hats (Gelugpa), Red Hats (Nyingmapa, Sakya), and Black Hats (Kagyupa).
The Dalai Lama belongs to the Gelugpa, which has been facing an internal revolt for many years from the Shugden sub-sect who believe that the pure Gelug teachings have been diluted by the Dalai Lama by the introduction of some Red Hat practices. These protesters are from the Shugden.