Sancho has been considered one of England's top young prospects for some time now and it took the City hierarchy by surprise when he turned down a lucrative contract with the club during the summer.
Speaking to 'The Sunday Times', the U17 World Cup winner revealed that it was Dortmund's commitment to youth develpment that convinced him to turn down offers from some of Europe's top club sides.
"I looked at who they have right now and the path," he explained.
"A lot of young players come to Dortmund and become top, top players. I thought to myself, 'Wow, that could be me'. I want to be part of that history.
"They're proving, by the games I've played, that age doesn't matter — they'll play you if you're good enough."
Ousmane Dembele's mega-money move to Barcelona saw the number seven shirt at the Westfalenstadion become vacant and the club didn't hesitate in handing it to Sancho, despite his tender age, a gesture that was well received by the youngster.
"To give me the '7' at such a young age really showed their faith," he admitted.
"Everybody just greeted me, it was chilled. Aubameyang, Gotze, Reus . . . just being normal. They [senior players] love my company and I love their company.
"Pulisic is only two years older, and what he has done for America, with big pressure on his shoulders, is an inspiration to me. When he plays, he treats it like it's easy, normal. That's how I want to be."