In Tableau, you when you are using two data sources, you have to join them using either the blend functionality or by using the new join functionality. Tableau will not be able to figure out which row to get the data from unless you do this first.
Unfortunately in Tableau you cannot join or blend the data using less than/greater than conditions. This is an idea proposed and under review: https://community.tableau.com/ideas/5583
Let me know if you have any further questions.