Looking on the internet deeply has found these results:

in the middle ages is the most popular phrase on the web.

at the middle ages 12,640 results on the web	in the middle ages 157,700,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	The unripe berries were used in the middle ages for torture. You won't believe it, but they boiled salmon underneath this in the middle ages. Although some countries are still living in the Middle Ages as regards compliance with human rights standards, Europe would be well advised to give up on adopting too arrogant a stance. But then I found a code written in the Middle Ages. Her family's still living in the middle ages. In the Middle Ages, Armenia was considered to be a major European power. in the middle ages it even incorporated an occult component and many alchemists were burned at the stake. You know, back in the middle ages, if you disrespected the King... you got killed.

at the middle ages

12,640 results on the web

in the middle ages

157,700,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

The unripe berries were used in the middle ages for torture.
You won't believe it, but they boiled salmon underneath this in the middle ages.
Although some countries are still living in the Middle Ages as regards compliance with human rights standards, Europe would be well advised to give up on adopting too arrogant a stance.
But then I found a code written in the Middle Ages.
Her family's still living in the middle ages.
In the Middle Ages, Armenia was considered to be a major European power.
in the middle ages it even incorporated an occult component and many alchemists were burned at the stake.
You know, back in the middle ages, if you disrespected the King... you got killed.