Economic hardships of the era, pervasive foreign presence, and religious proselytism by Christian missionaries in China: the causes of the Boxer Rebellion and the reasons for its extreme violence are manifold.

The Boxer Rebellion has its roots nearly 40 years after the Second Opium War (1856–1860). This post-conflict period is marked by the humiliation of Chinese defeat and powerful Western dominance. Foreigners led a privileged life in the concessions established by the Treaty of Nanking in 1842, territories where their home country's jurisdiction prevailed.

British, German, and French nationals in particular lived in quarters they had thoroughly claimed as their own, notably in Shanghai and on the outskirts of the Forbidden City in Pékin. China was also forced by Western powers to open its doors to free trade and international merchant vessels.

Very quickly, a hostile climate took hold. The Middle Kingdom suffered from divisions within the imperial power itself—between Emperor Guangxu and Dowager Empress Cixi—from the foreign presence materialized by the existence of legations, and from the "threat" represented by Christian missionaries, who converted nearly a million Chinese by 1900. Far from the Chinese capital lived an entire rural population left without work by the arrival of new foreign technologies such as railways, steamships, and the telegraph.

Westerners appeared to many as true "foreign devils" who disturbed the Fengshui, the natural balance of the world. The drought that gripped China from 1899 onwards and the famine it brought were indeed attributed by many Chinese to a Christian curse.

Strange rumors circulated that missionaries engaged in bizarre rituals to push back the clouds and perpetuate the drought. For their part, Westerners held little regard for the Chinese, whom they often viewed as servants they had to reluctantly share space with.