A reply to /u/HenkWaterlander ,

Maybe you can clarify what assertion you are questioning, because your wording is ambiguous. Are you suggesting that the Christian kingdoms of Iberia had very little among themselves before the Reconquesta? How do you determine "very little"?

Leon was united with Castile only after Ferdinand III of Castile invaded Leon following a succession dispute in 1230. This triggered insurrection by Leon loyalists.

Castile itself had a civil war in the 1360s over succession. Galicia was often disputed between Castile and Portugal, who were rivals all the way throughout most of the early modern era.

Due to its position, Navarre was often fought over and partitioned between rival powers. Following a civil war, Ferdinand II of Aragon, widow of Isabella of Castile, was able to obtain Papal support to invade Navarre and obtain kingship in 1513.

Speaking of Isabella, she became Queen of Castile only after overcoming invasion of Castile by Portugal due to succession crisis in the 1470s.

So, I'm not sure what assertion you are considering here. The list above isn't even nearly complete ....