Halakhah sobre Génesis 49:13

Even though it appears from the first outlook that the place the Hillazon is found is in the mountains so is stated in Tractate Sanhedrin (91a) 'He went up to the mountains and saw that today there was only one Hillazon, the next day it rained and the mountain was filled with Hillazon. And in truth in Tractate Menachot (44a) it says they emerge once in seventy years - Rashi explains: it emerges from the land and only in the mountain in the territory of Zevulun.