Pop Quiz!
The full description is here, and it's interesting reading, though the summary nature of the history strikes me, on first look, as a bit stretched and schematic. But if you're looking for a quick survey of the state of World-Systems theory scholarship, it's worth picking through a bit. Lots of good references.
Ultimately, it looks like they're trying to identify"global elites" which coordinate system-sustaining interests beyond and across national boundaries and using the social networks among national leadership classes to identify a global elite in the past which would make stronger their hypothesis that state-based hegemony is neither the full explanation for previous world-systems shifts nor the future of the world-system.
And if you think that's a bit unclear, well you should read the original first. Or skip it, and think about who you would put as the top ten"political power elite" (including military and economic figures) for your country of specialization during the following eras:
- 1840-1860
- 1860-1880
- 1880-1900
- 1900-1920