ויקרא כו,ו: דיִּרֲחַמ ןיֵאְו םֶּתְבַכְ שּו ץֶרָאָּב םֹולָ ש יִּּתַתָנְו רֹבֲעַת־אֹל בֶרֶחְו ץֶרָאָה־ןִּמ הָעָר הָּיַח יִּּתַּבְ שִּהְו בְּאַרְ צְכֶם:
Baal HaTurim: The phrase "והשבתי חיה רעה" (I will cause the wildness of beasts to cease) has a Gematria of 1021 which is equal to the Gematria of the phrase "ואלו ארבע מלכיות בבל מדי יון אדום" (these are the four kingdoms: Bavel, Media, Greece, Edom (Rome)).
Based on Sefer Daniel, the Chachumim treated the Jewish exiles to four main periods. These four periods are known as the Four Kingdoms, each called by the name of the dominant empire in the world at that time. The first is called the Bavel Exile, began when Nebuchadnezzar, King of Bavel, conquered Israel and destroyed the first Bais HaMikdash. The second exile of Media-Persia began when that empire became the leading empire. Even though they allowed the Jews to rebuild the Bais HaMikdash, the Jewish stated existed as a vassal of this empire. The Greece Kingdom dominated and actively rejected Torah values. Finally, the rise of the Roman (Edom) empire marked the Galus where we remain till this day.
