The highly-rated defender was a man in demand last summer after enjoying a breakthrough year in Amsterdam.
Having spent just 12 months in Europe following a switch from Atletico Nacional in his native Colombia, the 21-year-old was acquired by Spurs in a £42 million deal.
Sanchez told Marca on his career path: "It's true that I was always linked [with Barcelona].
"There was an offer on the table, but you have to think about the conditions.
"I had just won the Libertadores and had to go to Barcelona's second team.
"Although I was sure that I would finish up in the first team, because I have a lot of confidence in me and my ability to achieve important things, I played 50 games at Ajax and [that was] what I needed."
He added: "The first person I spoke with was Pochettino and I had the chance to go to Italy, but Mauricio convinced me.
"He was a central defender and I feel I can trust him, as what he wants from me seems very reasonable.
"He speaks to you face to face and I try to listen to him a lot."
Sanchez is now looking to make his mark in England, while a fellow Colombian has joined the ranks at Barca in the form of Yerry Mina.
The 23-year-old has opted to embrace the fierce competition for places at Camp Nou, rather than ease his way into European competition elsewhere, with an international colleague backing him to make a positive impression in La Liga.
Sanchez said of Mina: "He deserves everything that is happening to him and he has the ability to play at Barcelona because he has a lot of quality.
"He knows how to play the ball and he takes advantage of his height and has scored many goals.
"He isn't under pressure, it might be a little difficult at first, because it is his first experience [in Europe] but I know him and I know he will do very well."