Colonialism is bad, right?
Wrong.
The Aztec Empire ran sacrifice at industrial scale. Excavations of the Huey Tzompantli, the skull rack next to the Templo Mayor, have uncovered hundreds of skulls of men, women, and children. Spanish eyewitnesses described tens of thousands. The Aztecs fought "Flower Wars" whose purpose was capturing live victims for the altar. Hearts were cut out of living people. Subject peoples hated Aztec rule so much that Tlaxcalans made up most of Cortes's army. The conquest was largely an indigenous uprising against an indigenous empire. The sacrifices ended under Spanish rule.
India: burning a widow alive on her husband's funeral pyre. British records from Bengal alone documented thousands of cases between 1815 and 1828. The British, with Indian reformers like Raja Ram Mohan Roy, banned it in 1829. When priests told General Napier it was sacred custom, he answered: my nation also has a custom, we hang men who burn women alive. You follow yours, we will follow ours.
India: Thuggee cults murdered travelers by the tens of thousands over centuries as offerings to Kali. It was a hereditary profession. William Sleeman's campaign in the 1830s wiped it out.
Slavery was a universal indigenous institution. Dahomey and Ashanti were built on slave raiding and sold captives for a thousand years to Arab traders before any European ship arrived. Pacific Northwest tribes held up to a quarter of some village populations as slaves and killed them ceremonially at potlatches. The Comanche ran a captive-raiding economy across the Southwest. What colonizers introduced after 1807 was the first attempt in history to abolish slavery globally. The Royal Navy's West Africa Squadron spent fifty years hunting slave ships and freed about 150,000 Africans. African kings protested. The King of Bonny complained that abolition was destroying a trade ordained by his gods and priests.
The Dahomey kingdom's "Annual Customs" beheaded hundreds of captives and slaves every year to honor dead kings. Documented by European visitors for two centuries. It ended when France conquered Dahomey in 1894.
Sailors called Fiji the Cannibal Isles. Chief Ratu Udre Udre kept a stone for every victim he ate. His pile holds nearly 900. Shipwrecked sailors were killed and eaten. Within a generation of missionaries and British administration after 1874, the practice was gone.
Nigeria: In parts of Igboland, newborn twins were left in the bush to die and their mothers ostracized or killed. Missionary Mary Slessor spent decades in Calabar rescuing abandoned infants until the practice collapsed.
Indigenous genocide of indigenous people. In 1835, two Maori tribes invaded the Chatham Islands and slaughtered the Moriori, whose own law forbade them to fight back. They killed, enslaved, and ate them. The Moriori population fell from about 2,000 to barely 100. No European did this. British colonial law ended it.
Add headhunting in Borneo, the Philippines, and Nagaland. Female infanticide in India and Polynesia. Foot binding in China, dismantled partly by missionary campaigns. Every one of these ended under pressure from the colonial powers we are taught to treat as history's unique villains.
Colonialism was not charity. The Belgian Congo was a horror, conquest was for profit, and rule was without consent. But the ledger has two sides and one has been erased. Pre-colonial societies practiced slavery, human sacrifice, widow burning, infanticide, and genocide, because cruelty is not a European invention. The first civilization that tried to abolish these practices worldwide is the one you were taught to be ashamed of.
If "indigenous" means innocent and "colonizer" means guilty by definition, that is not history.