Complex sentence: The sons of king Haihaya, who was otherwise known by the name of Vitahavyas, invaded the kingdom of Kasi and advancing to that country that lies between the rivers Ganga and Yamuna, fought a battle with king Haryyaswa and also slew him in it.
Split into simpler sentences: The sons of king Haihaya, who was otherwise known by the name of Vitahavyas, invaded the kingdom of Kasi. Advancing into that country that lies between the rivers Ganga and Yamuna, he fought a battle with king Haryyaswa and also slew him in it.