Historian John Bagot Glubb authored a series of books about the history of the Arabs and their respective empire offshoots and areas of influence. He also wrote many essays within his work about how the any empire in question seems to enjoy a period of undisputed supremacy ranging close to 230 years, although he also suggested 250 and 200 years in other parts. These two century high achieving spans were then followed by 600 years of decline, and also mentions 1000 years until renewal. A plausible explanation he arrives at is the frequency of wars, ergo, dispatching manpower with lethal consequences. Anyone could win or lose a battle, but to keep up the effort of achieving victories after 200 years would not only have compromised resources and territory, but also drained the most able from a potential pool of recruits eventually leaving the less able to somehow hold the line and needing to do more with less at hand.

He cites similar cases with the roman empire, the spanish, the byzantines, and several modern europeans including the British. the recruitment policies are also mentioned and discussed, but not consistently in regards to the equipment. He makes good points about the excess of mercenaries in some cases, but (for an example) the roman military almost totally neglected armour, machinary, and improvising fortifications during the crisis years leading to the demise of the western empire