Answer by taking a quote from the following article:

Leander was born in Calcutta, India, on 17 June 1973 to Vece Paes, a Goan, and, Jennifer Paes, from Calcutta. He was educated at La Martiniere Calcutta, and the St. Xavier's College of the University of Calcutta. His parents were both sports persons. Vece was a midfielder in the bronze medal-winning Indian field hockey team at the 1972 Munich Olympics.

The duo of Leander Paes and Mahesh Bhupathi were nicknamed the ''Indian Express''. Leander Paes' off-and-on partnership with Bhupathi drew constant media attention in their home country India. In the 2006 Asian Games, a loss to the Chinese Taipei team in the team event led Leander to question Bhupathi's commitment to Team India. He once stated in an interview that although he and Bhupathi are friends, he did not consider pairing with his former teammate. However, for the 2008 Beijing Olympics, they decided to play together for their country, and lost in the quarterfinals to the eventual champions Roger Federer and Stanislas Wawrinka.  In 2011, the "Indian Express" pair won the doubles title at Chennai Open. They reunited to play in a Grand Slam Tournament after nine years and claimed runners-up in the 2011 Australian Open and reached the semifinals in the year-end championships.  The Indian duo has a 303-103 career record together. They have a higher success rate against various top teams. They have a Davis Cup record of longest winning streak in doubles, with 24 straight wins.  Leander Paes was paired with Vishnu Vardhan at the London Olympics 2012, following the refusal of Mahesh Bhupathi and Rohan Bopanna to play with him at the Olympics. Paes threatened to withdraw from the Olympics rather than play with Vardhan, whose world ranking was 296, but withdrew the threat a week later. Paes and Vardhan reached the second round of the tournament, losing to eventual silver medalists Michael Llodra and Jo-Wilfried Tsonga of France.

when did this partnernship start?