This study aims to elucidate various form of diplomatic courtesy of the early Great Mongol Empire (Yeke Mongγol Ulus) court and to analyze diverse foreign cultures, or subcultures, of the Mongolian steppe culture. After Qubilai Qa’an moved the imperial capital to Qan Baliq, growing numbers of foreigners visited the Empire and cooperated with the Imperial government. But this phenomenon has a specific periodical background and this study has elucidated the fact that there were already a large group of foreigners from various cultures before or after the foundation of the Mongol Empire. Among them were merchants, warriors, priests, envoys, clerks, interpreters, translators, and prisoners of war(peasants and artisans). Cosmas from Russia made the throne and seals for an enthronement ceremony G?y?g qa’an and Guillaume Buchier from France made ‘m?ngg?n modu’, which is a sort of a water fountain providing five different kinds of drinks. After the establishment of the Empire, there was a bigger necessity for a construction of an administrative system, therefore, administrationists of various origins like Tatatongγa, ?igi Qutuqu, ?inγai, Kadac, and Bala built the administrative foundation of the Empire. Historical records made by western priests visited the Mongol Empire were used as an important source of the elucidation of the diplomatic courtesy of the Imperial Court in this study. Envoys had to get off their horses hundreds meters before the palace and waited for an order from the prime clerk of the court. After the order of entrance arrived, they had to get through a security check. They were specifically warned not to step on thresholds in the palace. In front of the Great Qa’an, they had to fall on their knees and talk to the Qa’an through interpreters or vassals. Plano de Carpini was fortunate enough to have a competent interpreter, but William of Rubruck was not too lucky and he had to trouble himself to communicate with Monglians. This suggests that Europe was not regarded as an important diplomatic partner by the Mongol Empire. There is a letter from M?ngke Qa’an sent to Louis IX still exists and this letter has a specific wording of the Qa’an’s official order, which starts with “In the power of the everlasting God(m?ngke tngri-yin k???n-d?r)”. And one can also have a glance at the declaration of the conquest of the world from the letter.