Year 351 BC was a year of the pre-Julian Roman calendar

Roman calendar

The Roman calendar changed its form several times in the time between the founding of Rome and the fall of the Roman Empire. This article generally discusses the early Roman or pre-Julian calendars...

. At the time it was known as the Year of the Consulship of Peticus and Crispinus (or, less frequently, year 403 Ab urbe condita

Ab urbe condita

Ab urbe condita is Latin for "from the founding of the City ", traditionally set in 753 BC. AUC is a year-numbering system used by some ancient Roman historians to identify particular Roman years...

). The denomination 351 BC for this year has been used since the early medieval period, when the Anno Domini

Anno Domini

and Before Christ are designations used to label or number years used with the Julian and Gregorian calendars....

 calendar era

Calendar era

A calendar era is the year numbering system used by a calendar. For example, the Gregorian calendar numbers its years in the Western Christian era . The instant, date, or year from which time is marked is called the epoch of the era...

 became the prevalent method in Europe for naming years.

Persian Empire

• Encouraged by a failed effort at invasion of Egypt
  Egypt
  Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
  
   by King Artaxerxes III, Phoenicia
  Phoenicia
  Phoenicia , was an ancient civilization in Canaan which covered most of the western, coastal part of the Fertile Crescent. Several major Phoenician cities were built on the coastline of the Mediterranean. It was an enterprising maritime trading culture that spread across the Mediterranean from 1550...
  
   and Cyprus
  Cyprus
  Cyprus , officially the Republic of Cyprus , is a Eurasian island country, member of the European Union, in the Eastern Mediterranean, east of Greece, south of Turkey, west of Syria and north of Egypt. It is the third largest island in the Mediterranean Sea.The earliest known human activity on the...
  
   revolt against Persia
  Achaemenid Empire
  The Achaemenid Empire , sometimes known as First Persian Empire and/or Persian Empire, was founded in the 6th century BCE by Cyrus the Great who overthrew the Median confederation...
  
  .

Greece

• Demosthenes
  Demosthenes
  Demosthenes was a prominent Greek statesman and orator of ancient Athens. His orations constitute a significant expression of contemporary Athenian intellectual prowess and provide an insight into the politics and culture of ancient Greece during the 4th century BC. Demosthenes learned rhetoric by...
  
   tries to get the Athenians to cease depending on paid mercenaries and return to the old concept of a citizen army. He also delivers his first Philippic
  Philippic
  A philippic is a fiery, damning speech, or tirade, delivered to condemn a particular political actor. The term originates with Demosthenes, who delivered several attacks on Philip II of Macedon in the 4th century BC....
  
  , warning Athenians of the folly of believing that Philip's
  Philip II of Macedon
  Philip II of Macedon "friend" + ἵππος "horse" — transliterated ; 382 – 336 BC), was a king of Macedon from 359 BC until his assassination in 336 BC. He was the father of Alexander the Great and Philip III.-Biography:...
  
   ill health will save Athens from the Macedonians. In response, Athens' citizens votes for increased armaments.

Roman Republic

• The Etruscans are badly defeated by the Romans
  Roman Republic
  The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...
  
   and abandon their attacks on the city and sue for peace.
• First use of the heavy throwing spear, the pilum
  Pilum
  The pilum was a javelin commonly used by the Roman army in ancient times. It was generally about two metres long overall, consisting of an iron shank about 7 mm in diameter and 60 cm long with pyramidal head...
  
  , (according to Livy
  Livy
  Titus Livius — known as Livy in English — was a Roman historian who wrote a monumental history of Rome and the Roman people. Ab Urbe Condita Libri, "Chapters from the Foundation of the City," covering the period from the earliest legends of Rome well before the traditional foundation in 753 BC...
  
  ) in battle against the Gauls
  Gaul
  Gaul was a region of Western Europe during the Iron Age and Roman era, encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine. The Gauls were the speakers of...
  
  .
• The first Roman plebeian is elected to the office of censor
  Censor (ancient Rome)
  The censor was an officer in ancient Rome who was responsible for maintaining the census, supervising public morality, and overseeing certain aspects of the government's finances....
  
  .