It never ceases to amaze me that our not-so-friendly neighbor to the south keeps forgetting that TEXAS, all by her lonesome kicked their butts, badly the first time time Mexico decided to tangle with us. Then in the blowout Mexican War (1846-1848), after the Alamo and after Mexico relinquished Texas they still didn't like the idea of our expansion and so it was like this:
"The Americans took the offensive, invading Mexico on three fronts: from the north through Texas, from the east through the port of Veracruz and into the west (present-day California and New Mexico). The Americans won every major battle of the war, mostly thanks to superior artillery and officers. In September, 1847, American General Winfield Scott captured Mexico City: this was the final straw for the Mexicans, who finally sat down to negotiate." SOURCE
Thus speaketh the history teacher, once again preparing to teach American History starting this Monday!
Mexico’s current whining is perhaps just a feeble reaction to the butt hurt they suffered as mentioned in your history lesson. :)
Don’t forget the 1854 Gadsden Purchase, wherein many former Mexicans became land OWNERS, instead of just having land grants from the government, which could be seized at anytime by the government.