Ever Hayarden Hamizrachi - Eretz Israel?

Shalom Ubracha!!! In these parashiot that passed, it appears a lot about the nachala of Reuven Gad Vchatsi Hamenash - that lived in the ever hayarden hamizrachi. From what I understood, it isn´t part of Eretz Israel. My questions: 1- Is it Eretz Israel or not? 2- If not, how can it be that these 2 1/2 shvatim didn´t live in Eretz Israel? We know that all the aim of fourty years in the Midbar was to enter the Holy Land. After they had managed to realize it, 2 1/2 shvatim don´t enter! I know they had reasons for it: in ever hayarden hamizrach was better for their children and animals, but is it a reason for not entering Eretz Israel? Of course into Eretz israel there was enough place for them!!?? Thank You!

These two tribes were obviously not big zionists and did not understand the spiritual importance of being in the land of Israel. They wanted material things so they opted for a better material life outside the land of Israel. They were also the first tribes to go into exile. Pity.