The Incas used various methods to unify their empire. They introduced a common language, Quechua, which helped facilitate communication across different regions. They also implemented an extensive system of roads and bridges, known as the Inca Road, which allowed for quick transportation of goods and troops. Additionally, they established a strong centralized government with an emperor at the top, who ruled over several provinces. The Incas also used marriage alliances with local rulers to forge political and social connections throughout their empire.
