Did Arahath Mahinda Introduce Buddhism to Sri Lanka ?

The answer is "No" ! Buddha visited Sri Lanka on three occasions.On all these occasions he must have preached something.Buddha does not preach anything except dhamma.Mahayana scriptures have records of a scripture named "Lankavatara Sutta"It is said have been preached to king Ravana at Adams Peak.Apparently there has been several king Ravanas by way of a dynasty.The sutta contains Buddhas teachings in the most profound form.However"Lankavatara sutta" has not been featured in the Theravada Pali cannon.

Arahat Mahinda was responsible for establishment of Buddhism in Sri Lanka but he did not introduce Buddhism to Sri Lanka.It was done by Buddha himself.