Thessaly, in itself a purely Hellenic district as well as Aetolia and Acarnania, was in the imperial period separated administratively from the province of Achaia and placed under the governor of Macedonia. What holds true of northern Greece applies also to Thessaly. The freedom and autonomy which Caesar had allowed generally to the Thessalians, or rather had not withdrawn from them, seem to have been withdrawn, on account of misuse, from them by Augustus, so that subsequently Pharsalus alone retained this legal position;[197] Roman colonists were not settled in the district. It retained its separate diet in Larisa, and civic self-administration was left with the Thessalians, as with the dependent Greeks in Achaia. Thessaly was far the most fertile region of the whole peninsula, and still exported grain in the fourth century; nevertheless Dio of Prusa says that even the Peneus flows through waste land; and in the imperial period money was coined in this region only to a very small extent. Hadrian and Diocletian exerted themselves to restore the roads of the country, but they alone, so far as we see, of the Roman emperors did so. * * * * * [Sidenote: Macedonia.] Macedonia, as a Roman administrative district under the empire, was materially curtailed as compared with the Macedonia of the republic. Certainly, like the latter, it reached from sea to sea, inasmuch as the coast as well of the Aegean Sea from the region of Thessaly belonging to Macedonia as far as the mouth of the Nestus (Mesta), as of the Adriatic from the Aous[198] as far as the Drilon (Drin), was reckoned to this district; the latter territory, not properly Macedonian but Illyrian land, but already in the republican period assigned to the governor of Macedonia (iii. 44) {iii. 42.}, remained with the province also during the time of the empire. But we have already stated that Greece south of Oeta was separated from it. The northern frontier towards Moesia and the east frontier towards Thrace remained indeed in so far unaltered, as the province in the imperial period reached as far as the Macedonia proper of the republic had reached, viz. on the north almost as far as the vale of the Erigon, eastward as far as the river Nestus; but while in the time of the republic the Dardani and the Thracians, and all the tribes of the north and north-east adjoining the Macedonian territory, had to do with this governor in their circumstances of peaceful or warlike contact, and in so far it could be said that the Macedonian boundary reached as far as the Roman lances, the Macedonian governor of the imperial period bore sway only over the district assigned to him, which no longer bordered on neighbours half or wholly independent. As the defence of the frontier was transferred in the first instance to the kingdom of the Thracians which had come under allegiance to Rome, and soon to the governor of the new province