The Taungoo-Mrauk-U War  ) was a military conflict that took place in Arakan  from 1545 to 1547 between the Taungoo Dynasty and the Kingdom of Mrauk U. The western kingdom successfully fended off the Taungoo invasions, and kept its independence. The war had a deterrence effect: Mrauk U would not see another Taungoo invasion until 1580. The war's origins can be traced back to 1542 when King Min Bin of Mrauk U provided military support on the side of the Kingdom of Ava in the Taungoo-Ava War . Although Min Bin left the alliance in the same year, King Tabinshwehti of Taungoo was determined to repay the favor. In 1545, Tabinshwehti agreed to aid Min Aung Hla, the former Viceroy of Thandwe, who had been removed from office by Min Bin. In October 1545, Tabinshwehti sent a 4000-strong army but it was promptly driven back. Much larger Taungoo naval and land forces  tried again in the following dry season. The invasion forces overran southern Arakan, and were about to breach the defenses of the capital of Mrauk U when Mrauk U forces opened the sluices of the city's reservoirs, flooding the invaders out. On 30 January 1547, the two sides agreed to a peace treaty that allowed an orderly withdrawal of Taungoo forces from Arakan. The uneasy peace would last for the next 33 years.
Question: What happened first, Tabinshwehti sent a 4000-strong army or Taungoo forces withdrew from Arakan?
Answer: Tabinshwehti sent a 4000-strong army