The Ivorian switched to the Etihad Stadium in 2010 from Barcelona, but the French coach revealed the midfielder nearly played in the Premier League much sooner.
Toure, whose brother Kolo became captain at the north London club before leaving in 2009 for the Citizens, had agreed to join the Gunners according to Wenger.
“I have known him since he was 15,” Wenger told reporters ahead of his side's visit to Eastlands on Sunday.
“We had an agreement with Yaya to come here, but the problem was that he was at Beveren and we had to wait long enough for a European passport.
“Therefore he was impatient and went, at the time, to Metalurh Donetsk.
“Now he is a top-class player. We knew that at the time he would be a top-class player but the only problem with Yaya was to fix him into a position because he can play everywhere.”
The Gunners boss also commented on the 28-year-old's versatility on the field, admitting he was at first unsure of his best position.
He said: “He can play centre-back, as a second-striker, as a midfielder and for a long time we didn’t know where to play him.
“He played in a pre-season home at Barnet as a second striker – and he was completely average on the day.”