The Hungarian language is the most important source for reconstructing the West Old Turkic language spoken west of the Ural in the 5th–12th centuries. The study by Árpád Berta and András Róna-Tas deals with the etymology of about 500 Hungarian words which are or may be of Old Turkic, in some cases of Middle Turkic origin. The Hungarian–Turkic contacts began in the 5th century and lasted a long period. The earliest loanwords were copied from a Western Old Turkic idiom; the latest loanwords were borrowed from the language of the Cumans who settled down in Hungary in the first half of 13th century. The authors excluded the Ottoman words from the corpus. In all cases the authors give the etymology of the Turkic word, the reconstructed copied form, the form as adapted by the Hungarian language and the history of the word. The detailed introduction focuses on the former research, the historical setting and the technical framework. In the concluding chapters the authors reconstruct the Ancient Hungarian language at the time of the Turkic–Hungarian contacts and outline the structure of the West Old Turkic language. A bibliography and several indices help the reader to use the book.