Byattaba (; ; also Byat-Hta-Ba) was the ruler of the Martaban province of the Martaban–Hanthawaddy Kingdom from 1364 to 1388. He came to power by staging a coup against King Binnya U with the help of his brothers. Their rebellion led to the relocation of the Mon-speaking kingdom's capital to Pegu (Bago) in 1369. In 1364, Byattaba, then a senior official, seized the Martaban province south of Donwun while his brother Laukpya seized the entire Bassein province. In 1371/72, the rebel brothers and the king signed a treaty that allowed the brothers to be his nominal vassals. In 1384, the brothers refused to extend the same recognition to Binnya U's son and successor Razadarit. Unlike Laukpya, Byattaba did not help Ava in the northern kingdom's two invasions against Pegu in 1385–1387. Nonetheless, he was driven out of Martaban in 1388 by Razadarit. He fled abroad, never to be heard from again. Early life According to the chronicle Razadarit Ayedawbon, Byattaba was the eldest son of Saw E Pyathat, a general in the Martaban army. His personal name was Nyi San (ညီစန်, ), and he was probably born in the early-to-mid 1320s. He was a half-cousin, twice removed of kings Saw O (r. 1311–1323) and Saw Zein (r. 1323–1330). He had three younger brothers: E Bya Bon, Laukpya and U-Lo, and at least one younger half-brother, Ma Lagun. Their father died in action in the late 1320s against a war with Prome, a vassal state of Pinya. Saw Zein decided to look after Pyathat's children. The king died in 1330 but his promise to take care of Pyathat's children was honored by subsequent monarchs. Nyi San apparently was in sufficiently high social standing that he was given the title Byattaba, and was allowed to marry Princess Tala Mi Ma-Hsan, daughter of Saw Zein and half-sister of Binnya U (r. 1348–1384). Byattaba's star continued to rise in the early reign of Binnya U. In the first five years of U's reign, U faced two internal rebellions and an external invasion by Lan Na. Byattaba and his brothers were loyal to U, and the king reciprocated. By the early 1360s, he had brought the two elder brothers—Byattaba and E Bya Bon—into his inner circle, and appointed the third brother Laukpya governor of Myaungmya, a key port in the Irrawaddy Delta. The king personally married Byattaba's daughter Tala Thazin Zaw Ngaik, and Laukpya's son