Anyone interested in historical novels, check out these - Yavana Rani, Kadal Pura and Raja Muthirai. All by an author called Sandilyan.
Kalki’s books are a bit slow paced with phenomenal dialogues, beautiful prose and amazing descriptions. Sandilyan writes short, punchy dialogues and his novels are fast paced. They are both good, but Kalki is better and more authentic. Well with your time.
If you know Tamil, please read them in Tamil, not translations. Kalki especially is not easy to translate.