One of the earliest examples of a successful genocide, where there seems to have been a concerted effort to systematically destroy a group of people, can be found in the book of Deuteronomy in the Bible. It talks of a coalition of cities led by King Sihon of the city of Heshbon, in modern day Jordan, fighting against the Israelites. Deuteronomy 2:33-5 reports the one-sided conflict and what happened afterwards:

And the LORD our God delivered him before us; and we smote him, and his sons, and all his people. And we took all his cities at that time, and utterly destroyed the men, and the women, and the little ones, of every city, we left none to remain: only the cattle we took for a prey unto ourselves, and the spoil of the cities which we took.

Of course, there is no way to confirm how devastating this genocide actually was in the quantifiable way we can attempt to do with modern genocides. Saying this, if we go by the only source on the conflict, then the fact that the Israelites 'utterly destroyed the men, and the women, and the little ones ... we left none to remain' suggests that this was a largely successful attempt to systematically destroy a large group of people.

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