Why did the Roman Empire fall?
A slave based society can not pass through the next stage of economic development which is industrialization. No need to make a work saving device, just get more slaves. - ( I put this before barbarian invasion because if the Roman empire was able to grow economically it could make up for so many failures on the battlefield. )A slave based society amplifies the difference between the haves and have nots. Not just between slaves and freemen, but between rich slave holders and poor unemployed freemen. This greatly reduced the amount of stake holders within the Empire. Why should you fight to defend a society you have no stake in?The Emperor system neither produced good Emperors on a regular basis or allowed for a peaceful line of succession. Civil War is the most wasteful and dangerous of enterprises when faced with an outside enemy.The Emperor system also needlessly added to the states bureaucracy. Just one example is Governor-ships. With each new Emperor political favors need to be payed back and new Govern-ships where created until the ranks of Governors swelled beyond what would of been recognizable in the 1st century.In the 3rd century AD, for reasons not completely understood today central Asian horsemen poured out to of the Russian steppe pushing Germanic tribes in front of them, pressing them up against the Empire.Extended conflict along the Rhine/Danube, and the extensive use of Germanic mercenaries allowed a technology transfer to such a degree that by the 4th century it was difficult to tell the difference from a German in the Roman army and one that was fighting the Roman army.The reopening of the Silk Route allowed the freer movement of goods and ideas, but also plague. Plague ravaged the Empire who’s densely populated cities where highly vulnerable.These pressures and mismanagement pushed the Roman tax system beyond the Laffer curve optimum. Taxes where pushed higher, revenues fell and then taxes where pushed higher again. The currency depreciated and the amount of silver used in the coinage was reduced by dilution.
How did the British colonize India?
Britain came in the 1600s (with Sir Thomas Roe) when India was under the rule of Jehangir. India was a stronger nation back then. So, the British were contended to be traders. However, Nadir Shah's (of Iran) invasion of India in 1738, changed the picture (See: http://en.wikipedia.org/wiki/Nad...). The Mughal rulers were badly defeated and that signalled to the world that India was very weak. The East India Company immediately latched on and made use of the weakness. The timing was key. India had plenty of infighting. For instance, Tipu Sultan, who offered ferocious resistance against the Brits was undermined by our own rulers (Nizam of Hyderabad and Marathas) who surrounded the Mysore kingdom when British attacked him. The Marathas duly paid the price for the friendship with the devil with the Anglo-Maratha war in which they were badly defeated. British troops were well organized and used superior tactical & strategic skills on the warfield. French revolution and later the defeat of Napolean in 1815, distract the French from expanding their control in India. The British used this opportunity to kick out the other colonial powers from India.By the 18th century, India was under a crisis. The Aurangzeb's rule was quite bitter for non-Muslims and the Hindus were tired of Islamic rule. This gave rise to many Hindu kings (such as the Marathas). The East India Company rightly used this period to increase the divisions with their divide and rule policy. India had a very weak navy. Unlike islands like Britain or Japan, we didn't have enough incentives to build a strong navy. Naval superiority helped the British to gain and build the critical ports of India (Bombay, Madras, Calcutta) and build the empire from there. Britian was entering the age of industrial revolution at around the same time (1750) when Indian empires were weakened. The economic strength from industrial revolution gave the Brits an upper hand.