RANITAL, India — Hundreds of Tibetan exiles pressed ahead yesterday with a march to their Himalayan homeland from northern India, defying a police ban on the demonstration against Beijing’s hosting of the 2008 Olympics.

The march, which started Monday, was expected to take six months, reaching Tibet during the August 8–24 Beijing games in a bid to turn the Olympic spotlight onto China’s often harsh 57-year rule over the Himalayan region. It was one of several events launched around the world Monday by Tibetans, commemorating their 1959 uprising against China. About 300 Buddhist monks also protested in the Tibetan capital, Lhasa, one of the boldest public challenges to China’s rule in recent years. India, apparently fearful that the march could embarrass Beijing and jeopardize warming ties between the Asian giants, banned the exiles from leaving the Kangra district that surrounds Dharmsala, the headquarters of the Tibetan government-in-exile. The local police chief said Monday the ban was a recommendation by the Indian government.