I am studying history right now and our professor show us an interesting video.

Here is the video I am referencing

Couple interesting things I noticed.

1. China and India has more population in most of the history starting from AD 1, what is the reason for this? Even in the zenith of roman empire it seems that Indian empires like Gupta and Chinese empires like Han and Jin have much more people than the middle eastern or western ones. This is especially surprising because the Romans are known for their metropolitan cities and the late Han and Jin period are known for their on going civil war and politic instability, in fact the situation got so bad that it lead to the sixteen kingdoms that culminate to massive population displacement by the northern nomads. If we also compare against other great empire in the history we find similar trends. Selucid, Parthian, Byzantine, Sassanid, Umayyad, Abbasid, Seljuk, Timurid, Ottoman, France, Britain, Holy Roman Empire, Lithuanian Common Wealth, Safavid......etc Its not really until the late 1600 to 1700 that European population begin to catch on to Indian and Chinese population.

2. Anatolia, Levant, Syria, Transoxiana and Egypt's population pales in comparison to China or India and to Europe as well. This is also surprising given that much of the big empires originate in the middle east before Mongol conquest devastated the region. In fact the period of 8th to 13th century in middle east is named the islamic golden age while the same period in europe is named the dark age. Yet we observe that european population is much greater than those of middle east and chinese and indian population is greater than european population.

This is weird

Maybe I overlooked some context and historical fact? Can someone enlighten me?