Gathering in the End of Days

How does Yaakov communicate with his sons when he requests them to gather? How does this request filter down to our times, as ou nation gathers back in Israel? What is behind the parallels of four of the tribes to the four kingdoms that had power over us? How do Daniel from Yehuda and Mordechai from Binyamin take away the power of Bavel and Madai? How do Levi and ultimately Yosef take away power from Yavan-Greece and Edom-The West? What is the idea behind the seven days of mourning for Yaakov that parallel the seven days of celebration that will occur when the age of Moshiach commences?