敦煌晚期石窟（曹氏晚期、沙州回鹘、西夏、元）的分期断代，是近年来敦煌石窟研究的热点问题，也是瓶颈所在，分歧较大，甚至出现完全不同的观点。为什么会出现这种情况？综观学术界的研究，制约敦煌晚期洞窟分期断代的核心因素有四 ：“绿壁画”的时代归属 ；沙州回鹘艺术的源流 ；洞窟游人题记与洞窟营建之间的关系 ；北区洞窟出土物的时代与莫高窟西夏、元时期营建的关系。解决好这四个方面的问题，才能清除敦煌晚期洞窟分期断代路上的拦路虎。仔细梳理可发现，此四个问题并不复杂，被学术界反复讨论的“绿壁画”可以延续到西夏前期 ；回鹘风格洞窟壁画艺术与“绿壁画”之间不是没有关系而是关系密切 ；游人题记的大量出现只能判断敦煌石窟整体的衰败和相应洞窟的时代下限 ；北区洞窟出土文物大量为西夏尤其是元时代的事实则充分说明到了元代莫高窟整体营建的停止。

The periodization and dating of the late-period Dunhuang grottoes (including those from the late Cao, Shazhou Uyghur, Western Xia, and Yuan periods) have in recent years become both a focal issue and a major bottleneck in Dunhuang grotto research. Scholarly disagreements remain considerable, with some views even standing in complete opposition to one another. Why has such a situation arisen? A survey of existing scholarship suggests that four key factors underlie this problem: the chronological attribution of the green murals; the origins and development of Shazhou Uyghur art; the relationship between visitors’ inscriptions and grotto construction; and the relationship between the dating of unearthed materials from the Northern Section and the construction of Mogao Caves during the Western Xia and Yuan periods. Resolving these four issues is the key to removing the major obstacles to the periodization and dating of the late-period Dunhuang grottoes. Through careful analysis, it can be found that these problems are not complicated when approached from a scientific perspective. The much-debated green murals can be reasonably dated to the early Western Xia period; the relationship between Uyghur-style mural art and the green murals is in fact remarkably close; the large number of visitors’ inscriptions can only indicate the overall decline of the Dunhuang grotto complex and the terminus ante quem of the relevant grottoes; and the predominance of artifacts from the Western Xia, and especially the Yuan, unearthed from the Northern Section sufficiently demonstrates that large-scale grotto construction at Mogao had ceased by the Yuan Dynasty.