I think the story of Ponniyin Selvan might have been referring to the 10th century AD because Raja Raja Chola or rather Arulmozhi Varman of Kalki's Ponniyin Selvan ruled the Chola kingdom from 985 AD to 1014 AD.You are right. The incidents happened somewhere in 970 AD - 975 AD. Uthama Chozhar ruled from that day till 985 AD, and after his death Rajaraja ascended the throne.Somehow it occurred to me that 900 - 1000 is called as ninth century rather than tenth. May be I have become too digital and started counting from Zero :-)Rajendra Chola, son of Raja Raja Chola, might have made some military gains during his North Indian campaign.Probably yes. It is said that the Chozha empire reached its peak during his reign. He might have made at least some short term advancements in the North.But this book was mentioning about the ancestors of Rajaraja planting "tiger flags" on the Himalayas. I doubt whether there is any reality in that.But I guess it would have been a wonderful experience for you to read such a novel from Kalki, whatever may be the history or the reality.Yes, it was a great experience. I am looking for Kalki's other two historic novels Shivakamiyin Shapadham and Parthipan Kanavu.