Given the question: Information:  - The Roman Empire (Koine and Medieval Greek:   , tr. ) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome was the largest city in the world BC AD, with Constantinople (New Rome) becoming the largest around 500 AD, and the Empire's populace grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time). The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title "Augustus", effectively marking the end of the Roman Republic.  - Bulgaria (tr. '), officially the Republic of Bulgaria (tr. '), is a country in southeastern Europe. It is bordered by Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, and the Black Sea to the east. With a territory of , Bulgaria is Europe's 16th-largest country.  - Legio undecima Claudia ("Claudius' Eleventh Legion") was a legion of the Imperial Roman army. XI "Claudia" dates back to the two legions (the other was the XIIth) recruited by Julius Caesar to invade Gallia in 58 BC, and it existed at least until the early 5th century, guarding lower Danube in Durostorum (modern Silistra, Bulgaria). The emblem of the legion is not known; it could have been, as all of the Caesar's legions, the bull or possibly the she-wolf lactating the twins.  - The Nervii were one of the most powerful Belgic tribes, living in northern Gaul at the time of its conquest by Rome. Their territory corresponds to the central part of modern Belgium, including Brussels, and stretched southwards into French Hainault. During their 1st century BC Roman military campaign, Caesar's contacts among the Remi stated that the Nervii were the most warlike of the Belgae. In times of war, they were known to trek long distances to take part in battles. Being one of the distant northern Belgic tribes, with the Menapii to the west, and the Eburones to their east, they were considered by Caesar to be relatively uncorrupted by civilization.  - Silistra (pronounced ) is a port city in northeastern Bulgaria. The city lies on the southern bank of the lower Danube river, and is also the part of the Romanian border where it stops following the Danube. Silistra is the administrative center of the Silistra Province and one of the important cities of the historical region of Southern Dobrudzha.  - Titus Pullo was one of the two Roman centurions of the 11th Legion (Legio XI Claudia) mentioned in the writings of Julius Caesar. The other soldier mentioned was Lucius Vorenus; they appear in Caesar's "Commentarii de Bello Gallico," Book 5, Chapter 44. Pullo and Vorenus were fierce rivals for promotion to "primus pilus", the most senior centurion in a legion. Both distinguished themselves in 54 BC when the Nervii attacked the legion under Quintus Cicero in their winter quarters in Nervian territory. In an effort to outdo Vorenus, Pullo charged out of the fortified camp and attacked the enemy, but was soon wounded and surrounded. Vorenus followed and engaged his attackers in hand-to-hand combat, killing one and driving the rest back, but lost his footing and was himself soon surrounded. Pullo in turn rescued Vorenus, and after killing several of the enemy, the pair returned to camp amid applause from their comrades.  - A Gallus (pl. Galli) was a eunuch priest of the Phrygian goddess Cybele and her consort Attis, whose worship was incorporated into the state religious practices of ancient Rome.  - Gaius Julius Caesar (13 July 100 BC  15 March 44 BC), known as Julius Caesar, was a Roman politician, general, and notable author of Latin prose. He played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire.  - Commentarii de Bello Gallico, also simply Bellum Gallicum, is Julius Caesar's firsthand account of the Gallic Wars, written as a third-person narrative. In it Caesar describes the battles and intrigues that took place in the nine years he spent fighting the Germanic peoples and Celtic peoples in Gaul that opposed Roman conquest.  - The Roman Republic was the era of ancient Roman civilization beginning with the overthrow of the Roman Kingdom, traditionally dated to 509 BC, and ending in 27 BC with the establishment of the Roman Empire. It was during this period that Rome's control expanded from the city's immediate surroundings to hegemony over the entire Mediterranean world.  - Lucius Vorenus was one of the two soldiers of the 11th Legion ( Legio XI Claudia ) mentioned in the personal writings of Julius Caesar . The other soldier mentioned was Titus Pullo . He appears , along with Pullo , in Caesar 's Commentarii de Bello Gallico , Book 5 , Chapter 44 . The episode describes the two as centurions , approaching the first ranks , who shared a bitter personal rivalry . It relates how Pullo charged the enemy ( the Nervii ) in the heat of battle . Pullo casts his javelin into one of the enemy from a short distance , but his belt is simultaneously pierced by a spear , preventing him from drawing his sword , and he is surrounded by other Nervii . Just then L. Vorenus , following Pullo from the fortifications , reached the site of the mêlée and engaged the enemy in hand - to - hand combat . After slaying one of the enemy and driving back the rest , Vorenus lost his footing on the irregular terrain . As the Nervii drew closer to him , Pullo came to his rescue . After slaying many of their opponents , the two retreated to the fortifications amidst roaring applause from their comrades .  - Claudius (1 August 10 BC  13 October 54 AD) was Roman emperor from 41 to 54. A member of the Julio-Claudian dynasty, he was the son of Drusus and Antonia Minor. He was born at Lugdunum in Gaul, the first Roman Emperor to be born outside Italy. Because he was afflicted with a limp and slight deafness due to sickness at a young age, his family ostracized him and excluded him from public office until his consulship, shared with his nephew Caligula in 37.    What entity does 'lucius vorenus' has the relation 'country of citizenship' with?
The answer is:
ancient rome