The Mongol Empire of the 13th and 14th centuries was the largest contiguous empire in history. Wikipedia

13th- and 14th-century empire originating in Mongolia Wikidata

An empire of the Mongols and Turkic peoples which existed in Asia from 1206 to 1368 and became the largest contiguous land empire in human history, stretching from Central Europe east to the Sea of Japan and from Siberia south to the Indian subcontinent and the Middle East. Wiktionary

Empire of the Mongols and Turkic peoples. Wiktionary (translation)