Sri Lanka's history of foreign contacts encompasses a documented series of diplomatic missions, commercial embassies, religious pilgrimages, and transoceanic voyages received by the island's monarchy from antiquity through the fall of the Kingdom of Kandy. Positioned at the central intersection of major Maritime Silk Road trade routes across the Indian Ocean, the island functioned as a vital trade hub connecting South Asia with the Mediterranean and the Middle East and East and South East Asia. Concurrently, Sri Lanka served as the primary custodian and international sanctuary of Theravada Buddhist scholarship, drawing monks, scholars, and envoys from across Asia to its monastic centers.
The island's early foreign relations during the Anuradhapura period (377 BCE–1017 CE) established enduring religious and diplomatic precedents. Most notably, the 3rd-century BCE Mauryan missions dispatched by Emperor Ashoka, led by Mahinda Thera and Sanghamitta Theri, officially introduced Buddhism to the island and established the sangha. Sri Lanka's strategic position also led to early diplomatic exchanges beyond the subcontinent, including formal embassies sent to the Roman Empire during the reign of Claudius, the arrival of the sacred Tooth Relic from Kalinga, and extended visits by Chinese pilgrims such as Faxian. During this era, the island maintained extensive maritime networks involving Tang China, the Byzantine Empire, and early Islamic trade networks under the Abbasid Caliphate.
Throughout the Polonnaruwa period (1017–1232) and subsequent eras, foreign engagements were heavily defined by dynamic religious interchange and shifting regional politics. Sri Lanka cultivated deep reciprocal ties with Southeast Asia, exchanging monastic delegations, scriptures, and royal embassies with the Pagan Kingdom and Hanthawaddy Kingdom of Myanmar, as well as the Lanna Kingdom and Ayutthaya Kingdom of Thailand, often to restore damaged ordination lineages (Upasampadā). The island's location and importance also attracted prominent medieval travelers, including Marco Polo, Ibn Battuta, and Giovanni de' Marignolli, as well as the armadas of the Ming treasure voyages under Admiral Zheng He, which resulted in the Ming–Kotte War of 1411 and significant geopolitical shifts in the Kingdom of Kotte.
From the early 16th century, foreign contacts transformed dramatically with the advent of European maritime expansion. Native rulers in Kotte, Sitawaka, and Kandy engaged in complex power struggles, treaties, and military alliances with rival foreign powers to secure military hegemony and territorial defense. Initial contacts with the Portuguese were followed by formal diplomatic alliances with the Dutch East India Company (VOC), as well as missions from Danish, French, and British envoys. These diplomatic overtures and military interventions culminated in the 1815 Kandyan Convention, through which the Kandyan nobility ceded the island's sovereignty to the British Empire, ending over two millennia of independent Sri Lankan monarchy and foreign diplomacy.
List of missions