In Exodus, God tells the Israelites to keep the Feasts twice: once before the episode with the golden calf and once after. Here’s a summary of the 7 feasts.
The time between the end of the Old Testament (400BC from the prophet Malachi) to the preaching of John the Baptist (25 AD) is known as the “intertestamental” period. Here’s an overview of what happened.
After the death of King Solomon, two of his sons, Rehoboam and Jeroboam, fought for the throne. When Rehoboam harshly raised taxes on the people, the 10 northern tribes rebelled and installed Jeroboam as their king, creating the northern kingdom of Israel. The two southern tribes, Benjamin and Judah, remained with Rehoboam and became the kingdom of Judah.