...that Aleppo and Rome were the first cities in the world with more than a million inhabitants. Now that I did a Google search I learned that Alexandria and Baghdad also had a population of one million in very distant times.

Moreover...

"In those days, in those distant days,
In those nights, in those far-off nights,
In those years, in those distant years..."

But Sumerians did not have metropolises with more than a million people.