Diplomacy is the art and practice of conducting negotiations between representatives of states. It usually refers to international diplomacy, the conduct of international relations through the intercession of professional diplomats with regard to a full range of topical issues. International treaties are usually negotiated by diplomats prior to endorsement by national politicians. David Stevenson reports that by 1900 the term "diplomats" also covered diplomatic services, consular services and foreign ministry officials.
Some of the earliest known diplomatic records are the Amarna letters written between the pharaohs of the Eighteenth dynasty of Egypt and the Amurru rulers of Canaan during the 14th century BC. Following the in c. 1274 BC during the Nineteenth dynasty, the pharaoh of Egypt and the ruler of the Hittite Empire created one of the first known international peace treaties which survives in stone tablet fragments, now generally called the Egyptian–Hittite peace treaty.
Relations with the government of the Ottoman Empire (known to Italian states as the Sublime Porte) were particularly important to Italian states. The maritime republics of Genoa and Venice depended less and less upon their nautical capabilities, and more and more upon the perpetuation of good relations with the Ottomans. Interactions between various merchants, diplomats and clergy men hailing from the Italian and Ottoman empires helped inaugurate and create new forms of diplomacy and statecraft. Eventually the primary purpose of a diplomat, which was originally a negotiator, evolved into a persona that represented an autonomous state in all aspects of political affairs. It became evident that all other sovereigns felt the need to accommodate themselves diplomatically, due to the emergence of the powerful political environment of the Ottoman Empire. One could come to the conclusion that the atmosphere of diplomacy within the early modern period revolved around a foundation of conformity to Ottoman culture.
One of the earliest realists in international relations theory was the 6th century BC military strategist Sun Tzu (d. 496 BC), author of The Art of War. He lived during a time in which rival states were starting to pay less attention to traditional respects of tutelage to the Zhou Dynasty (c. 1050–256 BC) figurehead monarchs while each vied for power and total conquest. However, a great deal of diplomacy in establishing allies, bartering land, and signing peace treaties was necessary for each warring state, and the idealized role of the "persuader/diplomat" developed.
From the Battle of Baideng (200 BC) to the Battle of Mayi (133 BC), the Han Dynasty was forced to uphold a marriage alliance and pay an exorbitant amount of tribute (in silk, cloth, grain, and other foodstuffs) to the powerful northern nomadic Xiongnu that had been consolidated by Modu Shanyu. After the Xiongnu sent word to Emperor Wen of Han (r. 180–157) that they controlled areas stretching from Manchuria to the Tarim Basin oasis city-states, a treaty was drafted in 162 BC proclaiming that everything north of the Great Wall belong to nomads' lands, while everything south of it would be reserved for Han Chinese. The treaty was renewed no less than nine times, but did not restrain some Xiongnu tuqi from raiding Han borders. That was until the far-flung campaigns of Emperor Wu of Han (r. 141–87 BC) which shattered the unity of the Xiongnu and allowed Han to conquer the Western Regions; under Wu, in 104 BC the Han armies ventured as far Fergana in Central Asia to battle the Yuezhi who had conquered Hellenistic Greek areas.
The Koreans and Japanese during the Chinese Tang Dynasty (618–907 AD) looked to the Chinese capital of Chang'an as the hub of civilization and emulated its central bureaucracy as the model of governance. The Japanese sent frequent embassies to China in this period, although they halted these trips in 894 when the Tang seemed on the brink of collapse. After the devastating An Shi Rebellion from 755 to 763, the Tang Dynasty was in no position to reconquer Central Asia and the Tarim Basin. After several conflicts with the Tibetan Empire spanning several different decades, the Tang finally made a truce and signed a peace treaty with them in 841.
In the 11th century during the Song Dynasty (960–1279), there were cunning ambassadors such as Shen Kuo and Su Song who achieved diplomatic success with the Liao Dynasty, the often hostile Khitan neighbor to the north. Both diplomats secured the rightful borders of the Song Dynasty through knowledge of cartography and dredging up old court archives. There was also a triad of warfare and diplomacy between these two states and the Tangut Western Xia Dynasty to the northwest of Song China (centered in modern-day Shaanxi). After warring with the Lý Dynasty of Vietnam from 1075 to 1077, Song and Lý made a peace agreement in 1082 to exchange the respective lands they had captured from each other during the war.