Biggest Empires

" I will say that the Spanish Empire was the largest one."

They also don't count.

"2, 3, 4, 5, 7, 9, and 10 were?"

2) Chinese dynasty from 618-907

3) Gokturk empire which occupied mongolia from mid 6th-8th century

4) Islamic empire

5) Asiatic hunnic empire that occupied mongolia from 3rd century b.c.-2nd century a.d.

7) Persian empire

9) Brief empire in mongolia established by Tang Shi Huai in the middle of 2nd century a.d.

10) Turkish empire that swept through the middle east in the 11th century, part of the reason the crusades are sent.

   The true  question is: " Which was the biggest empire considering only fertile lands and populated regions"

   The roman empire wins

 wrong :

 yes modern china is big, but ancient is not: remove neimenggu, xizang, xinjiang, heilongjiang  yunnan nor qinghai. So classical chinese size would only be 1.5 million.

 The yuan never had an empire including all modern china, check maps

 Don't forget that at this time romans only took the fertile and populated north africa.

 the small lowly populated part of iberia can't compared with the huge lowly populated and unfertile steppes 

 We're speaking about empire so it mean controled and administered territories, not tributary states( which generally don't bother themself making war, just sending some presents, considered by chinese dynasty as a sign of submission)

 Tibet(tufan on your map) has never been crontrolled by yuan administration, actually tibetan and mongols did have the same religion, but the dalai lama was tibetan and so was considered by yuan as the head of the religion. That why no expedition was ever send against qiang nation.

Huigu, xixia and nuzhen were only tributary states, they were independant states.

 Your map is uncorrect because it don't show the differences i just mentionned