original: They had extensive maritime trade contacts with the Roman empire.
simplifications: They had maritme trade contacts with the Roman empire They had large maritime trade contacts with the Roman empire. They had many maritime trade contacts with the Roman empire. They had trade contacts with the Romans. They traded with the Roman Empire. The common routes were by sea. They traded often by sea with the Roman empire. They had long boat trade contacts with the Roman empire. They had many trade contacts by sea with the Roman empire. They had many maritime trade agreements with the Roman empire. They had deep maritime trade ties with the Roman Empire.