234 The Imperial Government
priate relations with kings on the fringes of the Empire who were actual
orpotentialaggressors:weseethis,forexample,inthefamousinscription
ofSilvanusPlautiusAelianusfromTibur,whichindicatestheformalactsof
subserviencerequiredofkings,andtheroleoftheDanubeasthesymbolic
frontieroftheEmpire:‘‘[H]eledkings,whopreviouslywereunknownto
the Roman people or were hostile to it, to our side of the river,which he
guarded,topayhomagetoRomanarms’’;italsorecordsthatAelianustook
hostagesfromsomeofthemanddescribeshowheliftedthesiegeofCher-
sonesusbythekingoftheScythians.^22
Equally,thegovernorofthenearestmajorRomanprovincemighthave
tointervenetopreventwhatseemedtobetooclosecontactsbetweenallied
kings. The most notable example is, of course, the occasion in the early
a.d.40swhenDomitiusMarsus,thelegatus(governor)ofSyria,insistedon
thedissolutionofameetingofalliedkingscalledbyAgrippaIatTiberias:
thosewhoattendedwereAntiochusIV,thelastkingofCommagene,Samp-
sigeramus of Emesa, Cotys of Armenia Minor, Polemon of Pontus, and
Agrippa’sbrother,HerodofChalcis.^23
Whentheissuewaspotentiallymoreserious,thepoliticalrelationscon-
cernedbecametripartite,thatistosay,king-governor-emperor.Again,there
isawell-knowncasefromJosephus,whenCaesenniusPaetus,thelegatusof
Syria,wrotetoVespasianin72or73tosaythathesuspectedAntiochusIVof
CommageneofconnectionswithParthia.Vespasianwrotebackempower-
ingPaetustoactashethoughtbest,andtheinvasionandprovincialisation
ofCommagenefollowed.^24
Forthewholeperiod,roughlyuptotheendofthefirstcenturya.d.,when
alliedkingdomswereamajorfeatureofthestructureoftheEmpire,such
tripartiterelationsmusthavebeencommon.Wecatchapassingglimpseof
such communications in operation, though from the following period, in
Pliny’scorrespondencewithTrajanfromBithynia.Firstly,amessengerfrom
KingSauromatesoftheBosporusarrivedinBithyniawithtwoletters:one
forPliny,sayingthattherewasanurgentcommunicationforTrajan,towhich
Plinyrespondedbygivingthemessengeradiploma(apermittouseofficial
wagons)toassisthisjourney;and,secondly,theletterforTrajan,ofwhich
PlinylearnednomorethanthatitcontainednewswhichTrajanneededto
know.Finally,anambassador(legatus)fromSauromatesarrivedtofindPliny
inNicaeaandstayedfortwodaysbeforePlinysenthimonenroutetoRome.
22.ILS982.- Josephus,Ant.19,8,1(338–42).
- Josephus,BJ7,7,1–3(219–43).