Genghis Khan was not the only one that used the same route - the Scythians, Sarmatians, and the Western branch of the Huns marched that direction. He was not that special - the only thing special in him invading Russia is that he did it in the middle of WINTER!
There was a lesser branch of the Silk Road that ran through Kazakhstan, Turkmenistan, and into Russia. If second rate merchants on camels can move through that route - so can an army. It would be a hard slog - as evidenced by the 1907 Peking to Paris Road race & the 1908 New York to Paris Road Race - many cars failed in that region and did not make it.
There is the Burma route of the Silk Road into India. If Merchants can use it, so can an army.
Those are all nomadic steppe peoples. Qing armies in the 19th century used guns and cannons. Steppe nomad logistics worked a bit simpler than those of gunpowder armies who need to resupply in enemy territory. Not only that, nomads could move much faster and travel lighter. Qing military discipline was already in the gutter by this point and who wants to march thousands of miles across deserts, swamps, etc.?
Merchants!=armies. Merchants don't have complex supply chains, merchants don't travel in the tens or hundreds of thousands, merchants have intimate experience traveling the roads through the years and generations most of the army would never have known. Just because a bunch of 'second rate merchants' can use that route doesn't mean a massive army set on breaking an empire would be able to.
The Qing tried their luck in Burma. Didn't work out so well. Burmese, not very fond of the Qing after the invasion attempt.
In the thousands of years of Imperial Chinese history, not one Chinese empire has ever sent forces to India by land. The terrain is just too hostile for massed movement, especially for those without immunity to the diseases endemic to the region.
That is so true. Genghis Khan has always been somewhat overrated in my opinion. Attila the Hun did very much the same things Genghis did, he just invaded at a time when there weren't that many historians to record his deeds, unlike Temujin.
Attila had quite impressive accomplishments but his empire didn't survive him. Genghis Khan's empire outlived him and stretched from the Black Sea to the Yellow Sea and would not be surpassed in total area until the British six centuries later and is still the largest land empire to ever exist. I'm not well versed on the intricacies of their individual achievements and reigns but the duration and size of their empires are the most obvious differences.