The two Kagyu lineages - Marpa and Shangpa - have remained unbroken until today. Marpa Kagyu came to Tibet through Marpa and was being transmitted further until it reached Gampopa from whom various branch lineages developed. The 1st Gyalwang Karmapa, student of Gampopa, is the first master to leave indications on his whereabouts of the next incarnation, hence starting the tradition of conscious rebirth.
The Golden Rosary of Karma Kagyu lineage is upheld by The Gyalwang Karmapa, he is the cord which holds all the many beads of this rosary in harmony and union.
Equally responsible for the continuity of this unbroken lineage of transmission are The Tai Situ Rinpoche, The Jamgon Kongtrul Rinpoche and The Gyaltsab Rinpoche who guarantee that the lineage is passed on as pure as it has existed from the very beginning in times of absence or spiritual training of a new incarnation of The Gyalwang Karmapa. This order does not refer to the spiritual level of realization of all these teachers, more it describes their tasks within the lineage which they carry out to benefit all sentient beings.
excerpted from The Himalayas and Beyond