During his three-year stay, Thunberg perfected his Dutch and studied the culture of the Khoikhoi, (known to the Dutch as "Hottentotten"), the native people of western South Africa. The Khoikhoi were the first non-European culture he encountered. Their customs and traditions elicited both his disgust and admiration. For example, he considered their custom to grease their skin with fat and dust as an obnoxious habit about which he wrote in his travelogue: "For uncleanliness, the Hottentots have the greatest love. They grease their entire body with greasy substances and above this, they put cow dung, fat or something similar." Yet, this harsh judgement is moderated by the reason he saw for this practice and so he continues that: "This stops up their pores and their skin is covered with a thick layer which protects it from heat in Summer and from cold during Winter." This attitude – to try to justify rituals he did not understand – also marked his encounters with Japanese people.