Here is a synopsis of Judah's role in the bible, which may provide you with some insight.
God made a covenant with Abraham for land and seed (both many decendants and the Seed = Jesus). Abaham had Isaac, Isaac had Jacob and Esau. Esau did not choose God, and Jacob more or less did, so the covenant promise followed him. Jacob had 12 sons by 2 sisters-by-blood wives who were bitter rivals for his affection. Leah, the unfavored one, had a God-blessed womb. She had her first three sons and named them according to her hope that her husband would now love her more with this one. Then she had her 4th - Judah, who's name means, simply, praising God.
After the 12 sons were born - two from Rachel the favored wife, Joseph and Benjamin. Joseph was the favorite son, and the others (which included sons from his wives' servants) were jealous, so they threw him in a pit to die. Then some slave traders came by and Judah was the one who suggested they sell him. This is how Joseph came to Egypt, and eventually landed a second-in-command gig over the entire country, preparing for whole region famine and instrumental in saving the clan of Israel (Jacob was also named Israel at this point). In the midst of the famine, Jacob, back in Canaan, sent all his sons except Benjamin, his now favorite son since he thinks Joseph is dead, to buy food. Joseph benevolently manipulates them into coming to Egypt for salvation from starvation through a series of events in which Benjamin is required to go to Egypt. Jacob doesn't want him to go, but Judah steps up and promises his protection.
Much later, when the 12 tribes - names based on the 12 sons of Jacob - are layed out in the promised land, the tribe of Judah encompasses much of the southern part of the promised land, and little Benjamin just above it. When the nation of Israel split, the northern kingdom retained the name of Israel, and the southern kingdom took on the name of Judah, and included only the tribes of Judah and Benjamin. Judah was the last kingdom to fall into apostasy and be sent into exile. Most of the godly kings in the long series of kings of the northern and southern kingdoms came from the southern kingdom.
Also, Jerusalem is located in what was Benjamin's territory. Bethlehem is located in what was Judah's territory.