High-resolution oxygen isotope records over the last 2249 ka (MIS 1-86) have been obtained from cores from the upper section (105.08 m) at ODP Site 1143 (at a water depth of 2772 m) drilled in the Nansha area, southern South China Sea. The sampling resolution is at about 2 ka intervals, resulting in one of the best oxygen isotope records over the global ocean. The oxygen isotope curves, displaying details of Pleistocene glacial cycles, reveal a nearly 300 ka long stage of transition from a predominantly 40 ka to 100 ka periodicity. Therefore, the "Mid-Pleistocene Revolution" should be considered to be a process of transition rather than an abrupt change. Within the 100 ka glacial cycles, changes in tropical sea surface water were found to lead those in high-latitude ice sheets. Our comparisons show that ice sheet expansion and extension of the glacial stage in the Northern Hemisphere within the 100 ka cycles must have been driven not by ice sheets themselves, but by processes outside the high latitudes of the Northern Hemisphere.