In 1977 Crook led an expedition to Zanskar in the Himalayas of Ladakh, a pilot study focussing on polyandry. For several years, he and colleagues led further expeditions studying the geology, agriculture, social and family life and monastic practices in this remote, high-altitude region. He later returned with James Low, a Tibetologist fluent in the texts and language, to study the lives of Buddhist hermits in the mountains.