We have to remember that perhaps by 12000ybp L56 was likely already in Chile (https://archive.nytimes.com/www.nyti...ogy-chile.html).
The 12600 ybp Anzick-1 sample is a L56 descendant on the 12600 old FGC47595 branch [I use Ust Ishim to Anzick-1 block of SNPs for dating SNPs].
https://www.yfull.com/tree/Q-FGC47595*/
So it possible that upstream branches reached South Asia quite early too.