Rob Kardashian and Blac Chyna appeared to confirm their engagement on Instagram Monday night.

Rob Kardashian, Blac Chyna Engaged

Kardashian, 29, and Chyna, 27, both took to Instagram Monday night to share the news of their engagement after just four months of dating.

“YES !…!…!” Chyna captioned a smiling picture of the two, with her ring front and center.

A photo posted by www.Lashedbar.co (@blacchyna) on

Kardashian then shared a picture of his new fiancée holding a stack of dollar bills in one hand and flashing her new rock on the other.

????

A photo posted by ROBERT KARDASHIAN (@robkardashian) on

“They are so happy,” an insider told E! News. “Chyna’s been texting her friends how excited she is!”

Another source revealed that Kardashian had purchased the ring for China about a week ago and added, “They were serious from the time they started dating. He knew he wanted to marry her.”

Among those congratulating Kardashian and Chyna on their engagement is Chyna’s best pal – and Kanye West‘s ex-girlfriend – Amber Rose.

Congratulations to my Family @blacchyna and @robkardashian!!! Pease don’t let nothing or no one tear u guys apart!” Rose wrote on Instagram. “I never seen my sis so happy and I couldn’t be more happy for her! Sometimes we find love in the strangest places Lol God Bless you 2! Now let’s get this wedding together so y’all can start making some babies #TrueLove #putaringonitsouknowitsreal #BlacRob.”

The marriage will be the first for both Kardashian and Chyna. Chyna was previously in a longterm relationship with TygaKylie Jenner‘s on-off boyfriend – with whom she was 3-year-old son King Cairo Stevenson.

Read more about: