It was under the rule of this king that Armenia entered into close relations with Europe. Just as the Zoroastrian Persians and afterwards the Greeks had inflicted all kinds of persecutions on the Armenians in order to convert them to their religions, so also in the reign of Leo II. and for many years afterwards the popes of Rome did everything possible to make the Armenians join their Church. The popes promised the Armenians help against the Mohammedans, they even offered to organise a Crusade, but the first condition was that the Armenians should become Catholics. When the Armenians did not accept these advances, a number of Catholic priests came to Armenia and tried to convert them. These priests were called “Unitors.” At this time the Tartars (who were heathens) became very strong and conquered Persia. The Armenian king when this conquest took place was Hetum. This king, though he maintained friendly relations with the courts of Europe, attached little weight to promises emanating from these quarters; he therefore formed an alliance with the Tartars against the Mohammedans. He tried to indoctrinate his new allies in Christian ideas and almost effected their conversion to Christianity. That he did not quite gain his object is due to external causes. Hetum, in conjunction with the Tartars, fought successfully against many Mohammedan sultans, but the Egyptian mamelukes grew strong and the Tartars became Mohammedans (1302), whereupon enmity arose between them and the Armenians. Three Mohammedan races—Seljuks, Tartars, and mamelukes—one after another attacked Cilicia, devastating the country and plundering many towns. The Armenians asked assistance from the Pope and from European kings; help was promised from France, but it never came, so the Tartars conquered Cilicia and slew its king, who, however, was avenged by his youngest brother, Ashin, who collected an army and drove the Tartars out of the country (1308). The Mohammedan kingdoms became very powerful at this time. The mamelukes dominated, besides Egypt, Arabia, Palestine, and Syria as far as the Euphrates.