This will be an evolving post about an increasingly common issue and a source of endless confusion: moving tokens from Binance Smart Chain to other chains. The source of the problem is that addresses and tokens in BSC resemble addresses and tokens in Ethereum, and further that "chains" like Polygon are slightly skew of Ethereum while being based on it.

We could start with the flow of moving from Ethereum to BSC, as that is how many people started in the migration away from prohibitive gas fees on Ethereum. Most other chains have a gateway token that serves as a fundamental utility token, such as BNB for BSC, AVAX for Avalanche, SOL for Solana, and MATIC for Polygon. These tokens serve for transaction fees, which are albeit much lower than in Ethereum, as well as acting as a basic unit of exchange for acquiring other tokens on that chain. However, these gateway tokens have another purpose: most centralized exchanges such as Binance support a withdrawal method that is native to that token's chain.

Therefore, the start of the journey usually involves acquiring the gateway token on a major exchange, such as BNB, and then withdrawing it using the network of the target chain, such as BSC or BEP20. It would of course make sense to reverse the direction when going back to the exchange, but what about a destination like a private wallet that is set up for another chain?

Let's take the simple case of sending ETH from BSC to Metamask. It is not obvious that ETH on BSC is a derived form of ETH that is technically Binance-pegged ETH. It therefore makes sense that sending that to Binance is relatively safe, assuming you use the BEP20 receiving address for ETH. Where people get into trouble is sending the BSC ETH to an ETH wallet address, assuming that will work. That doesn't cross the gap from BSC into Ethereum, though the transfer could be recovered by setting up the destination wallet in a multi-chain wallet so you can see the amount sent to that address in BSC.

So the obvious pathway is to send the BSC ETH to Binance, and then send it to an Eth-based wallet using the ERC20 network. The cost of sending from Binance is high, so besides the inconvenience of the extra step, it is natural for people to avoid doing this. There is a more direct path that is somewhat cheaper, especially when ETH gas fees are low: Binance Bridge, which you can find here: https://www.binance.org/en/bridge

Nowadays, there are new protocols like Anyswap (https://anyswap.exchange/bridge) and Multichain (https://multichain.xyz/) that charge a fee for going from one arbitrary chain to another. These work fine but have a high minimum charge, so the convenience needs to be worth it.

Binance Chain Wallet is popular with BSC, and it can be used to recover an Ethereum wallet from a seed phrase or private key, allowing you to see a transfer that you thought was going to an Ethereum wallet. A word of caution: BCW has an auto-convert feature that can handle conversion from BSC or BEP20 to Binance Chain or BEP2, but it doesn't provide an option to add a MEMO, which is a personal identifier for BEP2 transfers. When sending BNB as BEP2 to an exchange or service, it may not make it to your account, and then the service provider's only option is to send it back. However, there is a support request involved and it's possible the service provider may not have received the transfer, or can't find it.

MetaMask can be configured with custom RPCs for a variety of chains, including BSC, Polygon, Fantom and Avalanche. Then you have the strange phenomenon that the same wallet address is associated with all these chains, and it seems even more natural to send from and to the same address, but of course a conversion across chains is required. The tools mentioned above can help.

Now for one more strange case: Binance once allowed MATIC tokens to be sent using the MATIC/Polygon chain, but that option seems to have been removed in withdrawals. Perhaps this makes business sense for Binance, as Polygon has gained in popularity apparently at BSC's expense. So MATIC tokens can be sent from Binance using ERC20, which puts them in an Eth-based wallet, but not in Polygon.

(The simple way to understand the difference between BSC and Polygon is that BSC is a copy of Ethereum, with some fundamental changes to make transactions faster and cheaper, while Polygon is a Layer 2 solution based on Ethereum but uses some optimizations to make it faster and cheaper. Many dApps that are migrating to BSC can just as readily migrate to Polygon, because both ecosystems support the Ethereum Virtual Machine. There is some sentiment about Polygon being more Ethereum-native, but it is currently not as decentralized and there are trade-offs with regard to security. Nevertheless, Binance is a centralized entity that doesn't really manage BSC in a centralized way, and it has different trade-offs.)

So back to the question of what to do with MATIC tokens in an ETH-based wallet... Polygon provides an Ethereum bridge that is relatively straightforward and it uses a minimum of ETH gas: https://wallet.matic.network/login/

The can be found at the top of the QuickSwap site: https://quickswap.exchange/#/swap

To use the MATIC bridge, login with an ETH-based wallet, then select the ERC20 token you want to move into Polygon. Once you confirm, you switch the network to MATIC. It is intelligent enough to know that MetaMask has mulitple chains configured. There is a gas estimate up front and the final cost can be less. It can take some time to do the conversion, up to a half hour in my experience, but it works at relatively low cost. The unfortunate problem is that Binance still charges the ERC20 cost to move tokens to an Eth-based wallet, but chances are that you have many ERC20 tokens that can be converted with the MATIC bridge, not just MATIC itself. In fact, the bridge may find many tokens you were not even aware were there, because MetaMask does such a poor job of adding tokens.

Image: Rubic Finance, knssr/Adobe Stock