While OS X supports a vast library of characters in its set of keyboards, Mongolian is missing. I would like to know if Mac OS (Yosemite) has a keyboard with a character set sufficient to type all Mongolian characters. If possible, I would prefer a keyboard that most resembles traditional Mongolian keyboards. Installing keyboard apps or extensions would be a last resort.
No, Apple has never provided a Mongolian keyboard layout with OS X (either cyrillic or traditional script). You will have to use one of layouts which can be downloaded and installed from the internet. Another example is