AR Rahman says in this news article,

“My previous film was ‘Warriors of Heaven and Earth’. This is a Chinese film. I had to fly between Chennai and London to complete the film’s re-recording. Chinese people like Mohana raaga. I had composed most of the tunes based on this raga and on Sindhu Bhairavi. They loved the tunes,” he said.

Interesting. Some googling ensued & revealed the following information about Mohana from this site.

Gamakas for all swaras. Found in Chinese, Japanese and Swedish music

Ilaiyaraja, from what I’ve read, is sometimes called Mohana Raja considering that many of his songs have been in this raagam. Some of my favorites:
Malargalil / Singer : SP Shailaja / Movie: Kalyanaraman (1979)
Meenkodi Thaeril / Singer: KJ Yesudas / Movie: Karumbuvil (1980)
Naanoru ponnOviyam / Singers: SPB, P.Susheela and S Janaki / Movie: KaNNil theriyum kathaigaL (1980)
Poovil Vandu / Singer: SPB / Movie: Kadhal Oviyam (1982)
Vei Vela Gopemmala / Singers: SPB, SP Shailaja / Movie: Saagara Sangamam (1984) [in Tamil, Vaan Pole from Salangai Oli].
and arguably, the best one:
Ninnukori Varanam / Singer: Chitra / Movie: Agni Natchathiram (1988)

I’m sure MSV has also some gems in this raagam, but from the songs I know about, the best one has to be Kamban Yemaandhaan / Singer: SPB / Movie: Nizhal Nijamaagirathu (1978)

Now, if only someone could come up with a list of Great Mandarin Hits in Mohana & Sindhu Bhairavi.