The return journey was even more trying; winter was coming on, and for nearly seven months the Pope's faithful envoys struggled on across the endless open plains of Asia towards Russia, resting their eyes on vast expanses of snow. At last they reached home, and Friar John wrote his _Book of the Tartars_, in which he informs us that Mongolia is in the east part of the world and that Cathay is "a country in the east of Asia." To the south-west of Mongolia he heard of a vast desert, where lived certain wild men unable to speak and with no joints in their legs. These occupy themselves in making felt out of camel's hair for garments to protect them from the weather. Again Carpini tells us about that mythical character figuring in the travel books of this time--Prester John. "The Mongol army," he says, "marched against the Christians dwelling in the greater India, and the king of that country, known by the name of Prester John, came forth with his army to meet them. This Prester John caused a number of hollow copper figures to be made, resembling men, which were stuffed with combustibles and set upon horses, each having a man behind on the horse, with a pair of bellows to stir up the fire. At the first onset of the battle these mounted figures were sent forward to the charge; the men who rode behind them set fire to the combustibles and then strongly blew with the bellows; immediately the Mongol horses and men were burnt with wild-fire and the air was darkened with smoke." We shall hear of Prester John again. For within a few years of the return of Friar John, another Franciscan friar, William de Rubruquis, was sent forth, this time by the French king, Louis, to carry letters to the Great Khan begging him to embrace Christianity and acknowledge the supremacy of the Pope. William and his chosen companions had a painful and difficult journey of some months before they reached the camps on the Volga of one of the great Mongol lords. Indeed, "if it had not been for the grace of God and the biscuit which we brought with us, we had surely perished," remarks the pious friar in the history of his adventures. Never once did they enjoy the shelter of a house or tent, but passed the nights in the open air in a cart. At last they were ordered to appear at the Court of the great ruler with all their books and vestments.