Vajrayana practice runs through a teacher. Its methods, deity yoga, in which the practitioner visualises and identifies with an enlightened form; mantra; the mandala; the subtle-body yogas, are transmitted by empowerment, and the relationship with the lama who confers it carries obligations that have no close parallel elsewhere in Buddhism. That structure concentrates authority in persons, and several of the tradition's modern difficulties follow from it as directly as its transmission does.
Tibet has four principal schools. Nyingma, the old school, traces itself to the eighth century and Padmasambhava. Kagyu dates from the eleventh, through Marpa and Milarepa. Sakya was founded in 1073, and Gelug by Tsongkhapa in 1409; the Dalai Lamas belong to the last. The nineteenth-century Rime movement worked deliberately across these boundaries. Reincarnate teachers, the tulkus, are identified as children and inherit the office and often the property of a predecessor, a system with no equivalent in any other religion.
Two disputes are unresolved. The Karmapa succession produced two claimants recognised in 1992, Ogyen Trinley Dorje and Trinley Thaye Dorje. The evidence turns on a prediction letter whose authenticity one side questioned and whose forensic examination the other declined. The two met in France in 2018 and have issued joint statements since, which is reconciliation rather than resolution.
The Dorje Shugden controversy concerns a protector deity whose practice the fourteenth Dalai Lama rejected as sectarian from the late 1970s and formally in 1996. Two monasteries separated in 2008 to continue it. The principal of a Dharamshala college was murdered in 1997 in a case Indian police linked to the faction, and a Reuters investigation in 2015 reported Chinese state financing of protest campaigns organised around the issue.