From the Wenja Village, if you follow the river up to the northeast portion of the map into the mountains, a cave can be found containing the skeleton of a Blood Dragon from Far Cry 3: Blood Dragon surrounded by a cluster of dragon eggs.
In the valley just south of the Wenja Village, a corpse laying on the hood of a crashed makeshift car can be found at the bottom of the lake at the western end of the valley. This car is a reference to the Canopysaurus cavemobile owned by Fred Flintstone in the animated series "The Flintstones".
Far Cry Primal uses an almost identical map layout to Far Cry 4. The map can't be the same area thousands of years apart, as Far Cry 4 takes place in the Himalayas while Primal is set in Central Europe.