The Shangpa Kagyu is known as the "secret" lineage and differs in origin from the better known Dagpo Kagyu schools of Tibetan Buddhism. The Dagpo Kagyud come from the lineage of Tilopa whereas the Shangpa lineage descends from Naropa's Sister Niguma as well as Sukhasiddhi. It was revitalized in the 20th century by the first Kalu Rinpoche, who had many students in Tibet and in the West.
Read more about Shangpa Kagyu: Origins, Practice and Doctrine