Egypt Grants Excavation Rights is an event following the decision The Valley of Kings. A great power has asked for permission to excavate the The grave of Tutankhamun, and 
Egypt has accepted it, with the event Excavation Rights Requested.
The events only option Excellent! improves relations between Egypt and the great power by 20 and gives the great power 5 prestige with an additional 0.1 prestige, while the excavation is ongoing.
The Ingame text states: The Government of Egypt has granted us the exclusive rights to excavate and investigate ancient ruins in the Valley of Kings. The potential discoveries there will prove an enormous opportunity for us to increase our scientific renown in the world.
Futher complications
After the excavation begins a long list of possible events can happen, with a long list of possible effects both positive and negative. They can give prestige and research points if a grave is found, give militancy, hurt relations with Egypt or demand further funding to name a few.
If the crownjewel of the excavation, Tukankhamons Tomb, is found it gives a staggering 1 year worth of research points as well as 30 prestige. It does however have a mean time to happen of 2000 months(166,7 years).