他早年经历的关于郑桓公的身份，史籍记载多有分歧。有三种说法：一说是周厉王之子，周宣王异母弟;；一说是周厉王之子，周宣王同母弟;；一说是周宣王之子。在此三种说法之中，第一种说法可信度最大，一般多被采用。 关于郑桓公的早年事迹，在史籍中不见记载。1980年11月，在陕西省长安县出土一件铜鼎，上有铭文。经专家考证，铭文记载郑桓公早年事迹，他曾率兵迎击进犯周朝边境的北方部族猃狁，并取得胜利，时间大约在周宣王十六年（前812年）至周宣王二十二年（前806年）之间。
受封郑国 周宣王二十二年（前806年），周宣王将郑地（今陕西华县东）封给弟弟郑桓公，建立郑国。 Zheng Zhou 20th year, the King of Zhou gave the land of Zheng (now in Shaanxi Huaxian East) to his brother, Duke Huan of Zheng, and established the state of Zheng.
Zheng Zhou 46th year (782 BCE), King Zhou passed away. His son and nephew to Duke Huan, Ji Gongyue ascended to the throne as King You. In his eighth year (774 BCE), King You appointed his uncle Duke Huan as Prime Minister in charge of national lands and population registry. Under this position, Duke Huan governed well and won over the hearts of people from all walks.
It is said that "The Poem" was written to praise Duke Huan. At that time, King You indulged in wine and women daily without governing affairs properly while favoring a concubine named Baosi who increased corruption among officials leading to more suffering for common people. The feudal lords also harbored rebellious thoughts against him.
Seeing this situation where royal authority crumbled further towards chaos with no hope for improvement by any means possible, Duke Huan began planning an escape route early on because he knew it would only lead into more disasters ahead if left unchecked. One day while discussing matters with Taishi Bo - a scholar who managed records at court - about potential places where they could flee from impending doom:
Duke: "What place can I retreat too?"
Taishi Bo: "Only eastwards beyond Lo River & southwards below Yellow River."
Duke: "Why so?"
Taishi Bo: "Those places are near East Guo State & Yi State respectively."
Duke's reply was positive when asked about going southward along the river flowing toward Jiang Province but Taishi replied negatively due to greediness prevalent there instead suggesting Chu might rise up eventually since their ancestors had contributed significantly during times past.
Thusly convinced by Taishi's advice after considering options elsewhere such as West or South regions which were deemed unsuitable due either being close enough or having greedy rulers themselves waiting for opportunities upon realizing future prospects within China under weakened leadership following decline after its peak period ending around 771 BC before final collapse occurred just four years later following assassination alongside other victims including himself during brutal attack led primarily by Shang Kingdom forces supported by nomadic tribesmen known collectively as 'Western Barbarians'.