It is important for us to realize that Jesus at this time is not traveling to Jerusalem (Luke 9:51) in order to die there, as so many Bible commentaries suppose. Rather, Jesus set his face as a flint to go to Jerusalem (Luke 9:51) in order to confront the religious authorities about his office as Messiah, and this happened to be the time of his third Passover of his public ministry. The Galilean Jewish authorities had already rejected Jesus as their Messiah (Luke 6:11; cf. Matthew 12:14, 23-24; Mark 3:22), and considered his claim to be demonic, or, put another way, evidence of insanity (Mark 3:21; cf. John 10:20). Nevertheless, Jerusalem hadn’t the opportunity to officially reject him, although they hadn’t shown any signs of receiving him as their Messiah up to this visit, either.
Luke tells us that an innumerable multitude (KJV) or many thousands (NASB) of people had gathered to listen to Jesus (Luke 12:1). One doesn’t meet with many thousands of people crowding around Jesus except at Jerusalem, where pilgrims from all over the Roman Empire and other parts of the world came to worship at the Temple during one of the Jewish annual holy day festivals. Here, Jesus spoke about leaven, something that was important at the time of the Passover. His words imply that this was the season of the Passover, which Jesus intended to celebrate at Jerusalem, just before he left Galilee (Luke 9:51). Therefore, the many thousands that crowed around him serve to emphasize further that he was at Jerusalem celebrating that Passover.
While Jesus may have met with a few hundred people at any one time outside Jerusalem, he could not have met with many thousands (G3461) of people elsewhere. The Greek word is murias (G3461) and is translated as tens of thousands in Jude 1:14, thousands in Acts 21:20 and ten thousand in Revelation 5:11. It literally means ten thousand. While it may refer to an indefinite number of people, it would stretch credulity to refer simply to a few hundred people that no one took the time to count. Estimates can be made simply through observation, and a crowd of a few hundred cannot be mistaken for a crowd of cir. ten thousand. Thus, Jesus could only have been in Jerusalem, during one of its annual holy days in order to have this many people stumbling over one another to listen to him.
As Jesus left the Pharisee’s home who had invited him to a breakfast or lunch (Luke 11:37; 12:1), the context of his teaching his disciples seems to be that the Pharisees and scribes followed after Jesus and were now doing their best to urge him on, provoking him, continually asking him questions in an effort to catch something in his words, whereby they might accuse him of evil (Luke 11:53-54). Jesus’ visit to Jerusalem at this time was characterized by conflict. The crowds seemed to be willing to listen to Jesus and perhaps accept him as their Messiah, but the Pharisees and scribes (lawyers) were holding them back through their opposition to him (cf. Luke 11:52).
Thus, Jesus presented himself to the Jewish authorities as their Messiah during this Passover season, one year prior to his crucifixion. The Jerusalem authorities officially rejected Jesus as their Messiah during this visit, and Jesus ended up drawing a line in the sand, as it were, saying the nation must listen to him or those who have rejected him (Luke 11:23), for there could be no middle ground.
 I do intend to discuss this at greater length when we come to Luke 13. I hope to show there the possibility of Jesus intending to ascend to Jerusalem in order to be crucified.
 See Strong’s Exhaustive Concordance and Thayer’s Greek-English Lexicon.