Complex sentence: The Chronicle of the Borok Kings were written in a book called the Rajratnakar, this book was originally written down in Kókborok using the Koloma script by Durlobendra Chontai.
Split into simpler sentences: The Chronicle of the Borok kings were written in a book called the "Rajratnakar". This book was originally written down in Kókborok using the Koloma script by Durlobendra Chontai.