I can post you dozens of western sources that native Indian variety of Tea was found in Assam. Now, stop amusing us.Typical indian antics, quoting from random indian source, how credible????
Try something more professional:
UK Tea Council - Tea - A Brief History of the Nation's Favourite Beverage
For All the Tea in China: How England Stole the World's Favorite Drink and ... - Sarah Rose - Google Books
The Great British Tea Heist | History & Archaeology | Smithsonian Magazine