The rationale behind this is purely financial, since this would help ensure a wide release in the burgeoning Chinese market. Box office sales in China grew 35% last year, making it the second-largest international market behind Japan. The Chinese government recently expanded their quota for foreign movies shown in their country from 20 to 34, although foreign productions still have a number of hoops to jump through to ensure a wide release in China. Iron Man 3 employed a similar tactic, shooting a portion of the film in China to become a Chinese co-production.
It isn't known how this will affect the story, which we reported earlier this week will take place four years after Transformers: Dark of the Moon. Ehren Kruger is still working on the script at this time, so we'll have to wait and see if China truly does play a major part in the story.
Transformers: Age of Extinction was released June 27th, 2014 and stars Nicola Peltz, Mark Wahlberg, John Goodman, T.J. Miller, Stanley Tucci, Kelsey Grammer, Sophia Myles, Jack Reynor. The film is directed by Michael Bay.