What were 5 different inventions brought by barbarians during the first invasions of the Middle Ages?

During the first invasions of the Middle Ages, various groups often labeled as "barbarians" introduced several significant innovations. They brought the stirrup, which revolutionized cavalry warfare by providing greater stability for mounted soldiers. The development of the heavy plow allowed for more efficient farming in Northern Europe, helping to increase agricultural productivity. Additionally, they introduced the concept of feudalism, which transformed social and political structures, and crafted new forms of fortifications, including castles, that enhanced defense against invasions.