John 6:4

Now the passover, the feast of the Jews, was at hand.

This is the key to the chronology of the chapter and shows that about a year had elapsed since the healing at the pool of Bethesda, just mentioned in the preceding chapter.

The passover ... explains the great throngs of people and also points to the Exodus when the Passover was set up, and making it an extremely appropriate time for the teaching on the bread of life, contrasting with the feeding of the people in the wilderness.