Huseng wrote:Mantrayāna was introduced in the 8th century into China and seems to have become somewhat popular, perhaps because of the mysterious theatrical appeal of it to the common people, but it was effectively doomed in 845 when Wuzong crushed all Buddhist institutions. Any sort of urban Buddhism with state sponsorship received a deep, and sometimes fatal, blow.
That is a bit of an exaggeration. Vajrayana was available in China in later ages too, including translation of tantras, and enjoyed state sponsorship under the Mongols and Manchus. But I think it's that since the Taoists already satisfied those who were looking for yogic and magical practices, there was little need for a new one.
"While teachers of the middle way, mind only, transcendent wisdom, mantra, and other schools may have their own assertions, the fulfillment of those intentions is the same. There is not a single thing that is not contained within mind."
(Gampopa to Düsum Khyenpa, in "The First Karmapa", KTD Pub, p254)
“If you recognize the world of appearance and existence as the mind, realize the mind itself as empty, and have no grasping at the superiority of your realizations — this is the ultimate view."
(Chegom Dzongpa, in "The Book of Kadam", Wisdom Pub, p609)