Somdet Chao Phraya Borom Maha Prayurawongse (Thai: สมเด็จเจ้าพระยาบรมมหาประยูรวงศ์; RTGS: Somdet Chao Phraya Borom Maha Prayurawong; 1788 - 26 April 1855) or Dit Bunnag (Thai: ดิศ บุนนาค; RTGS: Dit Bunnak) was a prominent political figure of Siam during the mid-19th century as a regent for King Mongkut kingdom-wide.

He became a Somdet Chao Phraya — the highest rank a Siamese noble had attained during the Rattanakosin Era, with honor equal to that of royalty.

He was also known as Chao Phraya Phraklang (Thai: เจ้าพระยาพระคลัง), or Minister of Trade, and dominated Western affairs of Siam during the reign of King Rama III.

His father, Bunnag, or Chao Phraya Akkamahasena (Thai: เจ้าพระยาอรรคมหาเสนา), had served as Samuha Kalahom the Prime Minister of Southern Siam during the reign of King Phutthayotfa Chulalok.

Prayurawongse was a member of Bunnag family who descended from Sheikh Ahmad, a Persian minister during the reign of King Prasat Thong (His lineage had converted to Theravada Buddhism in mid-eighteenth century.).

In 1818, the Grand Palace expanded south and the Bunnags moved to new residence on the West bank of Chao Phraya River in the Kudi Chin district.

In 1819, Carlos Manoel de Silveira, Portuguese delegate from Macau, arrived in Bangkok and established first Western contact of Rattakosin period.

King Rama III then assigned the post of Samuha Kalahom to Phraklang without officially investing him with the title.

In 1831, Tunku Kudin,[6] nephew of Sultan Ahmad Tajuddin Halim Shah II, staged a revolt in Kedah, took control of Alor Setar and was joined by Patani.

Both Phraklang and Bodindecha marched along the Bassac River towards Saigon and met Vietnamese fleet at Vàm Nao.

In March 1847, the Teochew societies, known as Tōa Hia, of Samut Sakhon rose in rebellion and kill one of the royal guards.

Phraklang and his son Kham marched royal guard regiment to subjugate the Chinese at Samut Sakhon.

During the reign of King Mongkut, Prayurawongse officially held the post of both Samuha Kalahom and Kromma Tha.

His another son Kham was deputy of Kromma Tha (he was later made Chao Phraya Thipakornwongse) the Ministry of Trade.