Club-record £100m signing Tonali revealed that he took "10 minutes" to decide to join Spurs after a meeting manager with Roberto de Zerbi at his home.
The Italian said De Zerbi's vision and style of play convinced him that Tottenham was the right move, despite the side finishing a spot above the relegation for two seasons in a row.
Tonali, Anthony Gordon, Bruno Guimarães and now manager Eddie Howe have departed Newcastle who are falling apart this summer.
Speaking on his move, Tonali revealed that his deal was about getting the most money for the Magpies who are in need of a spectacular rebuild before the season starts in less than a month’s time.
"The first thing was to get the best deal for Newcastle.
"I met there some of the best people for football. They love football. They live for football. When I decided to move, I said to my agent and to Ross Wilson that I wanted the best deal for Newcastle because they deserve everything. This is football. Sometimes you have to understand how everything can change in your life in five minutes."
Italy move was impossible
Tonali then revealed that a move back to Italy was impossible as Serie A sides could not afford his £100M asking price.
"We stayed three years in Newcastle and after three years, we spoke all together, me and my family. It was impossible for the money.
"For the salary, you can speak all the time, but if you don’t find the money for the transfer, you don’t have the chance to move. England was our solution and we found the best solution in England for me, for my career, for my football, for my happiness, for my family. I spoke with two teams. I understood after 10, 15 minutes that Tottenham would be my next team."
Matthias Jaissle, current Al-Ahli manager, is expected to be appointed as Howe’s successor in the coming days in what feels like an impossible job.