Our carpenter completed some new book-cases and this led to our library being churned around a little. I found KPS Menon’s 1947 Delhi-Chungking: A Travel Diary about his 125-day 1944 journey from Delhi through Kashmir and Sinkiang/Xinjiang and “the 8th War Zone” to Chiang Kaishek’s capital at the time, Chung King/Chongqing. I had not read the book properly in decades. Looking at the contents, I found it said there were maps in the inside jacket — something I had never noticed before. Now I found the inner-jacket, put my hand in, and out came two Survey of India maps of Northern India (Kashmir, Baltistan), Sinkiang, China, Tibet….
I shall scan and upload them here within a day or so. It is clear that as of 1947 at least, China and Tibet were distinct on a map.