Helmut Hoffman states that the Ming upheld the facade of rule over Tibet through periodic missions of "tribute emissaries" to the Ming court and by granting nominal titles to ruling lamas, but did not actually interfere in Tibetan governance. Melvyn C. Goldstein writes that the Ming had no real administrative authority over Tibet, as the various titles given to Tibetan leaders did not confer authority as the earlier Mongol Yuan titles had. He asserts that "by conferring titles on Tibetans already in power, the Ming emperors merely recognized political reality." Hugh Edward Richardson writes that the Ming dynasty exercised no authority over the succession of Tibetan ruling families, the Phagmodru (1354–1435), Rinpungpa (1435–1565), and Tsangpa (1565–1642).