Before the Binance Exchange opened for trading, an Initial Coin Offering (or ICO) of BNB had already been taken place from June 26th to July 3rd for 11 days.
BNB was issued at 1 ETH for 2,700 BNB or 1 BTC for BNB.
Issued in the form of ERC-20 token, BNB has been running on the Ethereum Network and supplying with 200 million coins. However, in the face of the periodic burning events, the recent overall supply of BNBs is lower than 100 million BNBs which were offered in the ICO.
Even BNB is stemmed from the Ethereum Network, the ERC-20 BNB tokens will be swapped with BEP2 BNB under a 1-to-1 ratio. After all, the new BNB becomes the nation coin of the main Binance Chain and the mainnet swap was announced on April 18th.