When the Chinese character is written as 陳 or 陈, Tan would be how Minnan (闽南) (Hokkien, Taiwanese, Teochew) would normally pronounce this surname.
陳: Traditional Chinese, 陈: Simplified Chinese
Pinyin: Chén, Wade–Giles: Ch'en (Chen), Other: Chern,
Jyutping (Cantonese pronunciation): Can4, Hong Kong Government Cantonese : Chan, Other: Chun,
Min Nan (Hokkien, Taiwanese, Teochew):
Pe̍h-ōe-jī (Church Romanization): Tân, Other: Tan, Chan, Ting
Start of Surname Chen/Tan/Chin/Chan (陳)
Mǎngōng (滿公) (1045 - 985 BC) was enfeoffed by Zhōu Wǔ Wáng (周武王) to the area known as Chén Guó (陳國) in present day Henan province. Zhou Wu Wang did this after Mangong helped him defeat King Zhou of Shang, Shāng Zhòu Wáng (商紂王). Mangong was the progentior of the Chén family (陳). His posthumous title was Chén Húgōng (陳胡公). He was the First Marquis of Chen Guo. Mangong’s wife Tàijī (太姬) was Zhou Wu Wang’s eldest daughter. Mangong reign for 60 years.
The Early History of Chén (陳) and Chén State (陳國)
From our first generation ancestor Shùn Dí 舜帝 (born in 2255 BC) to one year before Chén Hú Gōng 陳胡公 was enfeoffed as the Marquis of Chén Guó 陳國 (1074 BC) is a period of 1181 years. Dividing this span by 34 generations gives an average of 34.7 years per generation.
When Marquis Huán Gōng 桓公 (of the 43rd generation) died in 719 BC during the Spring and Autumn Period internal conflict and contention for the marquisate ensued. The son of Lì Gōng 厲公, Wán 完 (courtesy name Jìng Zhòng (敬仲) fled to Qí Guó 齊國. From this point on there were frequent changes of marquises.
During the reign of Chéng Gōng 成公 (48th generation) the state was weak and became subservient to Chǔ Guó 楚國. In 480 BC Yuè Guó 越國 destroyed Wú Guó 吳國. Chǔ Huì Wáng 楚惠王 seized this opportunity and marched north to attack Chén Guó 陳國. Mǐn Gōng 湣公 died during his reign. There were a total of 20 generations with 25 marquises lasting for 588 years.