There was simply no need to industrialize in India. In addition, the British invasion and colonization of India did not help industrialization efforts, and although a few scattered factories surfaced, India could not industrialize. China had very similar reasons for not industrializing as India.
Isaac Hempstead-Wright, who has played Bran since Season 1, is currently 17 years old. Wright and the other child actors on Game of Thrones have continued to age at the same rate that everyone must biologically age at due to science, making it impossible for the characters themselves to age at the rate implied in the books.
Like all epic Game of Thrones battles, the showdown between the Stark and Bolton armies began with multiple strategy sessions, as Jon Snow (Kit Harington), Davos Seaworth (Liam Cunningham), and Tormund Giantsbane (Kristofer Hivju) did their best magic math to figure out how to beat an army twice the size of their own.