What if Tamerlane lived long enough to invade China as his plan?

What do you mean "less well trained Chinese army?"

During the Yongle reign, three training camps were set up to train infantry, cavalry (using Mongolian instructors) and artillery. Plus, how would 200.000 warriors succesfully siege a city with 900.000 defenders?  

Timur had superior cavalry, but all things considered the Chinese would have a decisive advantage. unlike during the earlier Mongol invasions, the great wall was in full operation, and was guarded with a variety of cannons, including five heavy bombards placed at each frontier pass. In addition, Yongle and his generals had extensive experience fighting nomad-type cavalry.

Ok, here is my take on this situation:

Timur missed the best time to attack China.  Three years prior to his campaign, China was in the process of civil war, with Zhu Di (the later Yongle Emperor) commanding his Northern armies South to take the Southern capital Nanjing, against his nephew, who was emperor at the time.  Zhu Di eventually won the civil war, but I can imagine the damage that Timur would be able to do to disrupt the Ming if he started three years in advance.

I have no doubt about the ferocity of Timur and believe that he is a good warrior.  I would place my bets on Timur if his army and the Ming army met somewhere in central Asia.

However, for an invasion of China, the situation would be different, due to logistical reasons.  The Ming Empire under Yongle Emperor was at its height and its armies had plenty of experience fighting against Mongols in the campaigns into Mongolia during the latter years of the 1300s.  After a century of Mongol rule, the Chinese population was extremely hostile against foreigners, especially Mongols and Persians.  Remember that it took the Mongols 40 years to take over the Song Dynasty in Southern China, and that the Song army was much. much weaker than the Ming army. 

Thus, my conclusion:

Phase 1

A. Timur would use his strengths to seriously damage the Ming Chinese garrisons and border troops in the west

B. Timur woud lay seige to a couple of cities in the western border of the Ming state, taking his time to rape and plunder

C. The Mongols would probably ally with Timur and lead an expedition south of the Gobi Desert

Phase 2

D. Emperor Yongle's strengths lay in the North (he was Prince of Yan and consolidated his power in the North), so he would not have too much trouble rallying his personal troops against the Mongols.  Yongle was a fierce commander who excelled in cavalry warfare.  He would either slaughter Mongols, scare them North, or sign a secret treaty with them.  (I am not exaggerating Yongle's ability and aggressiveness - the man could be as bloodthirsty as Timur at times.  If Timur is compared to Hitler, then Yongle would be compared to Stalin.  Yongle was above all a militant leader who excelled in killing, and was noted for his love of the martial arts.  As Prince of Yan, he was posted in Beijing for years to counter Mongols, and had personal experience fighting in cavalry warfare.)

E. Timur would rely on his blood and iron tactics to gobble up all the lands west of Tongguan Pass.  More rape and plunder follows.

F. The Chinese generals hold Tongguan Pass and Hanzhong, taking advantage of the mountaineous terrain.  Timur's cavalry would become useless at the chokepoints, and any further advance would result in falling into well laid traps.  Chinese reinforcements from the Southern and Eastern provinces would come to aid, barracading Tamerlane and preparing to launch a counter-offensive.

Phase 3.

G. Timur would realize that he had reached the extent of his campaign. He would be faced with three choices

1. Include the newly conquered western Chinese provinces into his empire, like the Mongols 

2.  Set up a vassal/puppet state under the nominial rule of a Chinese governor 

3. Rape, pillage, and plunder as much as he could and return to Samarkand with his loot.

If he chose 1, the populance would soon revolt due to widespread hatred of Mongol/Persian/Turkic rule, with the help of a strong, militarily versatile Ming Empire.

If he chose 2, the new vassal state would either declare independence or, most likely, be annexed back into the Ming.

The most logical choice would be 3.  Tamerlane would gain most by plundering while the Chinese troops are still in defensive stance and then withdrawing to Samarkand, becoming the richest man in the world and avoiding major losses to his troops.  The western borders of Ming China would be ravaged again on the way back.  It would take years for recovery and thus Tamerlane would secure his monopoly of the Silk Road.

Strategically, Tamerlane would win most if he attacked China, plundered, and swiftly returned to Samarkand before a counter-offensive of the Ming army could be organized.

That is, provided Tamerlane did not die on the way there (which he did)

Sidenote: Any mention of a battle in Beijing is unrealistic unless Tamerlane forms an alliance with the Mongols.  Tamerlane's army is marching from west to east; that means travelling from the Tarim Basin to Gansu and then into the Guanzhong region west of Tongguan Pass.  To reach Beijing via the speedest route, Tamerlane would have to either ally with the Mongols or subdue the Mongols to bypass the Tongguan Pass and attack Beijing via Mongolia.

Originally posted by Imperator Invictus Wow interesting stats. I wonder how  William Wallace got into a game about Genghis Khan.

You can play as England in this game.  In fact, you can play as any faction within the Eurasian continent. 

Firearms were not decisive weapons for victory until much later. And Tamerlane defeated quite a few powerful firearm-infantry based armies of the period, including those of Sultan Bayazit and those of the Delhi Sultanate.The decisive victorious weapons of the day still were the quick and enduring horses of the northern steppe and the Mongolian bow. But the real secret of Timur�s military success was his composite army, consisting of light Mongolian and heavy Central Asian cavallery, Indian elephants, infantry, fire arms, although invented in China but improved in the 14th century in India, western Asia and Europe, and advanced western Asian besieging technology. Depending on the military situation in a battle Timur was able to use one or the other of these weapons to reach a decisive advantage (f.e. elephants against Bayazid). Alexander the Great before him and Napoleon after him followed the same rule.

Chinese army had lot of experience to fight those huge animals like elephant. Dated back to more than 1000 years before Ming dynasty, chinese army had yet encountered and defeated the elephant based vietnam or Yue troops in the South Asia and South east Asia.

Chinese firearm technology was improved in only Europe. One 16thc European observed that Iranian soldiers were so unfamiliar with firearms that they were "Afraid of artillery beyond measure" (source: Firearms: a Global History to 1700, Kenneth Chase) they never made any such observations about the Chinese. Indeed, Chinese firearm technology was only surpassed in Europe by the late 15th century.

On a sidenote, where are your sources?

No way, Genghis had surprise and a weaker opponent.

At best his armies would have tired out sooner or later, the quality, numbers and home advantage of the Ming Army would have required constant tactical supremacy for several years in order to properly occupy China for generations to come.