A combined geochronological and paleomagnetic investigation has been performed on Paleocene volcanic sequences in the Lhasa block near the localities of Mendui (30.1°N/90.9°E). A total of 15 sites have been sampled from rhyolitic tuffs. Stepwise thermal demagnetizations successfully isolated high unblocking temperature characteristic directions. The tilt-corrected mean direction is D/I=359.0°/26.1° with α 95 =9.2° and N=14 sites, corresponding to a paleopole at 73.6°N, 274.3°E with A 95 =7.3°. Positive fold tests suggest a primary origin for the characteristic remanence. In order to provide a more accurate pole, we propose to combine site-mean directions from this study and Achache et al.'s (1984). The combined average palaeomagnetic direction from early Paleocene volcanic rocks is D=356.6°, I=25.9°, κ=21.7, α 95 =6.8° after tilt correction, N=22 sites, corresponding to a pole at 73.2°N, 282.4°E with A 95 =5.4°. The paleomagnetic results yield a paleolatitude of 13.6±5.4°N for the southern margin of Eurasia at ∼55Ma. Compared with expected paleomagnetic directions from the stable India and Eurasia blocks, significant crustal shortening of 1400±600km and 2000±550km respectively may have occurred between the southern margin of Eurasia and the stable India, and within Eurasia since the collision of India and Eurasia.