How old Indian system ayurveda is?

Ayurveda originated on earth in 2000 B.c itself, As great Sages like Susrutha, charaka many more written books called Samhitas on their names. Lord Dhanwantari bought Ayurveda at Ksheera Sagara Madana Period, shanku, chakra, amruta kalisa and leech in four hands. Here leech indicates for treatment purpose in natural way. So Ayurveda originated with deva gana its the system originated by god.