The MB itself records the events before MB from the earliest known king Barhi. Following groups and events are recorded in chronological order till MB War.
King Barhi's 13 daughters were married to Sage Kashyap. The decendents of these daughters formed various groups called Aaditya (Dev), Gandharv, Apsara, Daitya, Daanav, Asur, Naga and Manav.
A bitter fight arose between the Dev and Asur groups that continued for centuries. By MB times these two groups had separated geographically and there was little, if any, interaction between them. Only one Asur, Maya Asur is mentioned in MB. He constructed the Maya-Sabha for the Paandav. Historically, Asur (the Assyrians of Assyria / Persia) are mentioned in the recent times.
The Naga group had remained nuetral during the fight between the Dev and Asur. When Arjun and Krishna cleared the Khandav forest for habitation, many people of the Naga tribe were killed / displaced. This led to a bitter enimity between the Naga and the Kurus.
The Gandharva and Apsara's joined hands with the Dev. They had friendly relations with the Manav. Many of them are mentioned in the MB. Gandharva Like Chitrarath who helped the Paandav, or Chitrangad who fought and killed Shantanu's son Chitrangad, or Sairandhri's 5 Gandharva husbands during incognito. Apsara's like Menaka, Adrika and Urvashi also play a role in MB.
Dushyant-Shakunala, Sage Vishwamitra and Vashishtha all belong to the same period of Parashuram. After Parashuram ended the Satya Yug.
The next recorded battle is between Ram, the 102nd decendent of Manu, and Ravan of Lanka. This is also recorded in the Ramayan of Sage Valmiki. With Ram ended the Treta Yug.
After Raam, the Dasharadnya war took place. It was a war of ten kings, that took place between Panchal King Sudas, son of Divodasa, and 10 other kings. This event is mentioned in the Rg Ved. Paanchali (aka Draupadi) was a decendent of Sudas.