With the emergence of the concept of citizenship in the Greco-Roman world, the status of slaves and inhabitants of conquered territories during Classical antiquity became in some ways analogous to contemporary statelessness. In antiquity, such "statelessness" affected captive and subject populations denied full citizenship, including those enslaved (e.g., conquered populations excluded from Roman citizenship, such as the Gauls immediately following the Gallic Wars, or the Israelites under Babylonian captivity). However, there was a major difference between captive and subject populations in contrast to those living outside the boundaries of cohesive states - while both could be considered stateless, the latter typically only needed to adhere to local tribal customs whereas the former were not only expected to obey the laws of the state they were living in, but were often subjected to laws not imposed on and punishments not inflicted on full citizens. Among the more widely-known examples of this was the Romans' frequent use of crucifixion to punish Roman subjects, considered to be a highly degrading form of capital punishment that could not legally be inflicted on Roman citizens.