Zheng He rose within the household of the future Yongle emperor after being taken into Ming service as a boy. As a court eunuch he became a trusted official, and his support during the struggle that brought Yongle to power helped establish his standing. In 1405 he commanded the first of the large maritime expeditions sent from China into the South China Sea and Indian Ocean. His responsibilities combined fleet organization, imperial representation, and relations with overseas rulers.

Between 1405 and 1433 seven principal expeditions reached ports in Southeast Asia, the Indian subcontinent, and farther western waters. Later missions extended to the Persian Gulf, Arabia, and East Africa. The fleets carried large crews, soldiers, translators, and goods intended for exchange and diplomatic presentation. Their purposes included displaying Ming authority and incorporating foreign rulers into tributary relations. They followed existing commercial routes and depended on pilots, interpreters, and knowledge accumulated by many maritime communities rather than discovering previously unknown seas.

The voyages combined negotiation and trade with the use of force. Zheng He's fleet confronted piracy near Palembang and intervened in political disputes, including the capture of a ruler in Sri Lanka. Envoys and goods brought back to China demonstrated the reach of the court; unusual animals such as giraffes attracted particular attention. The familiar image of a peaceful explorer omits the military power that made the missions instruments of imperial policy.

After Yongle's death, changing priorities and the costs of distant expeditions reduced support. The final major voyage under the Xuande emperor sailed in 1431–1433. Accounts differ over the circumstances and date of Zheng He's death, which is conventionally associated with this last period. The end of the state expeditions did not eliminate Chinese maritime commerce, nor does it establish that China simply ceased all overseas contact. His career illustrates the capacity of the Ming state to mobilize resources for long-distance diplomacy and naval operations. Debates continue over the sizes of the largest ships and some reported details. A balanced account distinguishes contemporary inscriptions and participant narratives from later legends, recognizing both the impressive logistical achievement and the coercive purposes of projecting imperial authority across the Indian Ocean.