How to Build a bump chart in Tableau
Step 1:
Drag month of date to columns, and region to rows.

Step 2:
Create a calculated field called rank.
Rank(sum([Sales]))

Step 3:
Add rank to the text mark and set the table calculation to calculate for each month by checking region and unchecking month.

Step 4:
Move the region pill to color. Move the rank pill to the rows shelf, and copy it.