"Tea if by sea and Cha if by land" - that is how the etymology of the words for tea are traced back into China.
Chai is a complex subject! Firstly, to go back a bit, chai is another word for tea, used mainly in countries along the land trade routes for tea and spices out of China during the thousand years old Silk Road. The word originates from the Sinitic character 茶 which is pronounced ‘cha’ in the Mandarin language. This pronunciation eventually morphed into ”chay” (چای) in Persian as tea traveled across the continent. ‘Tea’ is the term used by trade countries that accessed China by sea - firstly the Portuguese, then Dutch and finally English trading ships. The Min language of the coastal Fujian people pronounce the character 茶 as ‘te’, which is the other widely used term for tea.
That leads us into the topic of South Asian cuisine. The countries in South Asia all use blends of strong spices in cooking and traditional healing. The Ayurvedic therapies found in the Hindu religion use complex herbal compounds for healing including many of the common spices still used today. The term Garam masala is a common term that literally translates as a hot blend of spices. Garam in the Ayurvedic sense refers to a heating in the body, as these spices are believed to elevate body temperature. The combination of spices in a Garam Masala, will of course not only change from region to region, but also person to person according to personal taste. Think of it as "Grandma's chocolate chip cookie recipe" that differs from family to family. Like any recipe, there is no ‘right’ way to make it, just what you enjoy. There are typical ingredients, of course, which can include any combination of the following: ginger, turmeric, fennel, peppercorns, cloves, cinnamon, nutmeg, cardamom, cumin, coriander, and sometimes star anise or chili. The amount of any ingredient depends on the blender and recipe or dish created.
Here in Canada and the United States, ‘Chai’ has morphed into a loose meaning of a spiced black tea very often sweetened with milk. This is largely accompanied by a very simplistic impression of South Asian tea culture, which clearly fails to take into account representation of individuals, subcultures and influences of colonialism on all of the above. Chai (or Chay) evolved in India during the occupation by the British. The British colonization of India gave the English the ability to monopolize the tea industry out of India by owning and growing native tea plants in Assam and Darjeeling.
Once the British began growing and producing tea in India, tea prices dropped and tea became accessible and popular with the locals. Chai was, and still is sold, within Indian markets through Chaiwalas, (tea sellers). British Tea culture influences of milk and sugar merged with Hindu Ayurvedic medicines, and much of the tea sold was also spiced. Each Chaiwala also combines their brew with their own mix of spices and brewing methods to appeal to the local markets. After Indian independence in 1947, chai culture, intertwined with the world's consumption of Indian arts and Bollywood, became the number one export earner of the country.
In North America, when someone speaks of 'Chai' or the redundant 'Chai Tea', they are almost always referring to our own adapted version of traditional India street chai. This can often refer to a "Chai Latte" which is typically made in a cafe with a spiced black tea and at least 50% milk, often steamed together created from a concentrate, or sometimes a tea bag of tea and spices brewed in milk. Some Indian or other South Asian restaurants serve a more traditional Chai, based on the region or recipe they might want to present. The quest for the most "authentic" chai can be misguided as such a drink still comes down to personal preference and influences, and like everything is always evolving and adapting to cultural changes.
I have created several blends of spiced black tea in The Tea Girl catalog, reflecting influences from tea culture in North America. The wording to me is complex. I still called it Chai, with the understanding that the term chai in western society means a certain style of spices with black tea leaves. However I do understand the word Chai anywhere else in the world is understood very differently, and there is not one recipe that can represent any culture.