Malbec is a French grape. It came to Argentina in 1853, did badly in Bordeaux, and then quietly became something else entirely once it was planted three thousand feet up against the Andes.
Altitude is the whole story. Thin air means more ultraviolet light, which thickens the skins and concentrates colour and tannin. Cold nights hold on to acidity that a warm valley would burn off. And there is almost no rain — Mendoza gets around nine inches a year, so the vines drink snowmelt through channels the Incas were using long before anyone planted a vine.
Open these four side by side and you can taste the climb. That's the point of this case.