This may seem like an ambitious undertaking, claiming to know the nature and leader of the last world government. I would never undertake such a task by logic alone. But the Bible lays it out very clearly. Here is how just two Bible books define it, though there are many, many, more details.
The geography involves the nations of the Roman empire. The ruler is a little man who becomes empowered by Satan. The duration of this government is 3 and 1/2 years. The Bible books that tell us this are Daniel and Revelation.
I may sound contradictory when I say that, we the church will not be on earth during the days of this government, yet pursue a study of it. It looks like others besides the church will use this divinely inspired guide in the Bible to understanding the last days--non-church people who remain after the rapture. But my immediate purpose is to help disprove a bunch of sloppy ideas being thrust upon us.
For example, there is presently a movement towards a one world government. Horrible as such a government will be, it is not the last one, the big one. Wrong territories, and the lack of the proper, or Biblical, leader, and the timing is off.
First, Daniel 2 gives us the makeup of this satanic empire, the nations of the Roman empire. This leaves out Canada, the United States, and Mexico. It also excludes South America, Japan, Russia, and China. Leaders of these countries are thus excluded, as are all prominent leaders everywhere. Why? Because the last leader starts out as small. The included nations are the subjects of the end time government because they are intimately connected with Israel.
I want very much to frame out the basics of the final government, its nations, and leader. This subject is dear to my heart. I have been immersed in it for decades. A little entry of mine cannot do it justice, but everything in it will stand up to, and be supported by, further study.