God gathered "them" back into the holy land for the purpose of punishing them.

Therefore this is what the Sovereign Lord says: ‘Because you have all become dross, I will gather you into Jerusalem. As silver, copper, iron, lead and tin are gathered into a furnace to be melted with a fiery blast, so will I gather you in my anger and my wrath and put you inside the city and melt you. I will gather you and I will blow on you with my fiery wrath, and you will be melted inside her. (Ezekiel 22:19-21)