This paper provides a comprehensive review of recent studies on the moisture sources of precipitation over the Tibetan Plateau and its surroundings, focusing on the characteristics of moisture sources (regions of evaporation) for precipitation, spatiotemporal changes in the contribution of moisture sources to precipitation, and the causes of changes in moisture source associated with the recent wetting trend over the Tibetan Plateau and drying trend in Southwest China which lies on the southeastern corner of the Tibetan Plateau. The existing studies show that the moisture transports from the west by the northern hemispheric middle latitude Westerlies and from the southwest by the Indian summer monsoon contributed the most to precipitation over the Tibetan Plateau. The moisture transports from the west shows a decreasing trend while that from the southwest and the east shows an overall increasing trend in the past three decades. The enhanced water vapor transport from the monsoon regions and the intensified local hydrological recycling is the primary reasons behind the recent wetting trend over the Tibetan Plateau, while the reduced water vapor transport from the regions dominated by the Westerlies is the main factor that causes the drying trend on the southeastern corner of the Tibetan Plateau. The challenges and future directions for understanding the variation of moisture source of precipitation over the extended Tibetan Plateau area are then discussed. Firstly, the observational evidence of the variation of moisture source is still lacking. There is a need to reduce uncertainty of the moisture source estimates through integration of model and observations. Secondly, the changes in glacier, lake, and vegetation over the Tibetan Plateau and the associated changes in evapotranspiration would affect water vapor transport and recycling. There is a need to quantify the interactions between land surface change and precipitation over the Tibetan Plateau and its surroundings from the perspective of water vapor sources. Thirdly, the enhanced moisture supply from the monsoons and reduced moisture supply from the Westerlies could be linked to climate change as the projection of future precipitation changes under a warming world showed the same pattern as the past three decades, i.e. a wetting trend over the Tibetan Plateau and drying trend on the southeastern corner. However, further research is needed to under-stand the linkages between global change and moisture source variations over the Tibetan Plateau and its surroundings.