Queen Chandra Nandini or ‘Niadrus’ (Greek Version)  is considered as the princess of  Nand Clan, Nanda Dynasty. Nanda Dynasty was found by Padmanand. Nandini the daughter of Nanda Dynasty. Queen Nandini was one of the three daughters of Dhanananda, the ruler of the Great Nanda Dynasty which ruled Northern India around 322 BC. 

According to reference in Jain Literatures Queen Nandini was married to Chandragupta Maurya as a war compensation and Dhanananda was sent to exile in the forest, became a Jain Monk. 

According to Megasthenes reference from Indika (greek: Indica) Niadrus was an exceptionally warrior and a great leader. Niadrus was the eldest of all descendants of Dhanananda. Niadrus was also the advisor of militia and an able army commander. Niadrus had a fleet of 2000 Elephants and 4000 Chariots.

Queen Nandini – Queen Niadrus – or Nandvansham Nandini – Treaty of Marriage with Chandragupta Maurya 

Around 323 BC, Chandragupta Maurya was looking for support to fight against Alexander. Chandragupta got support from Parvateshwar (Porus), ruler of Punjab. But, ruler Dhanananda did not support Chandragupta and ridiculed him. This got Chandragupta Maurya to prepare and overthrow the Nanda Dynasty. Chandragupta had a great clash with Nandini. The 4-day war ended with a treaty as Nandini agreed to marry Chandragupta Maurya in a pardon for Dhanananda’s Life, who was under 2-month old captivity of Mauryans. 

[Jatin Bhaskar book "Ancient Indian Dynasty" said Padmanand was royal Barbar of  Magadh. He had a illegal affair with Magadh king Paspak.  Suryagupta and King Paspak was a great friendship. Suryagupta was the king of Pipliban father of Emperior Chandragupta. Oneday Suryagupta was in Magadh for an invitation attent, he saw the Padmanand and queen Abantika (king Paspak wife) together in queen's bedroom. Then Padmanand killed Suryagupta and Paspak also. But queen Moorya got flying from palace of Magadh, meanwhile she gave birth a child (Chandragupta). Queen Moora conceal new born child on the way of Forest and Padmanad Army captured her without baby. Chandragupta was found an poor foster parents. His foster mother love him so much but father always insulted and bite him. Oneday Vishnugupta Chanakya (The Author of Arthashastra, Indian Philosopher, Teacher of Taxila University) came to Magadhto inform Dhananand for invation of The Greate Alexander (Sikandar for Indian Version, Zulkarnain for Arabic Version) and suggested Dhanand for taking action upon Alexander. But Dhanand brutally insulted Chanakya and threw him out of palace.  Returning way of Taxila Chanakya saw Chandragupta fighting with Magadh solder bravely then he followed him almost 1 month. Chanakya surprised Chandragupta's bold fower and kind heart upon inhabitants and country. Then he went to meet Chanragupta's father to home. But he saw his father tortured him as brutally. Then Chanakya bought him from his foster parents and gave training for upcomingfight against Alexander and take revenge from Dhananand. During his last training session Chanakya told Chandragupta to take train from Unani skills too. Then Chandragupta admitted to Alexander's Army as low level solders. After training session Chandra came back to Acharya Chanakya and collect solders to fight with Dhananand. Firstly 5 times Chandragupta lost the battled against Dhananand's Army.  Meanwhile The Great Alexander was died (Some Historians said Alexander was killed by Poison). Alexander army was shocked to get the sad news and his army was disarranged. Selucus Nicator was the General of Alexander's army. Chanakya suggest to attack Nicator at time and capture Selucus Nicator. Chandragupta defeated Selucus Nicator and his daughter Helena Nicator. Chanakya gave a proposal to Nicator to get marriage between Chandragupta and Helena thus Chandragupta get profit from Nicator's Army.  After marrying with Helena, Chandragupta's power and solders was increased and attacked upon Magadh's friendly States. Lastly Chandragupta about to know he is prince of Pipliban. Then he get more help and finally he got success to defeat Dhanand.]   

Queen Niadrus (Nandini) vs Helena ( Durdhara) [Geek Version-Diodora]

Around 322 BC, after the death of Alexander the Great, Greeks had started retreating from Asia leaving behind a bunch of Indo-Greek Kingdoms, one of kingdoms being ruled by Seleucus I Nicator, a Macedonian satrap of Alexander. Seleucus I Nicator involved himself in a peace treaty with Maurya Dynasty and married his daughter Helena (or Diodora or Durdhara) with Sandrocuttus(Chandragupta). Sandrocuttus favoured his Greek wife over his first wife Niadrus. Nandini who was already let down by Sandrocuttus overthrowing her father Dhanananda from the thrown was now furious. 

Niadrus's child Emperior Bindusar and Helena's (Diodora) child prince Justin Maurya

Niadrus was being dead for giving birth Bindusara got poisoning and Diodhara was got death penalty to against to killed teen Ashoka (The Great Ashoka). Diodara wanted Prince Justin son Siamak for next after Bindusara. But Ashoka kileed 99 brothers for gain the throne. [For revenge the killing of Guru Chanakya, His Mother Devi Dharma and Emperior Bindusara, all the killing plans was made by Prince Soojak (Shushim) and Jiagan (Siamak)] 

Chanakya wanted Bindusara to next reign for Magadh but Chandragupta favored Diodara (Helena) and he waned Justin for the next reign. The subjects of Magadh as well as whole India would not accept Justin for the next Mauryan Emperior. Some Historian guessed Sandrocuttus left the Palace for his reason and live in forest. Queen Nandini – Conversion to Jainism and Later Life  

--From: Indo-Greek Fallacy by Romert Dickens

[Some Historian said  some alternative comments It is depicted that Niadrus (or Nandini) poisoned Diodara which caused her death. Nandini was prisoned by Sandrocuttus and was later pardoned in her older age. Nandini also converted to a Jain Aryika in later life.]

NB List

1. Chandragupta Maurya married Helena first to overthrow the Greek. Durdhara was the daughter of Dhananand( whom Chandra defeated). The Nanda Clan was started by Mahapadmananda who was indeed a barber and killed the then king and became the ruler. Dhananand was one of his sons. Now, Durdhara was also called Nandini- meaning the daughter of Nanda or the princess of Nanda dynasty. After defeating Dhanananda, Chandra married Nandini. Chandragupta was given food with administered, small dosages of poison every day to make him immune as ordered by Chanakya. Nandini being unaware of this, ate from his plate and died immediately. Chanakya though reached in time and cut open her womb to save the unborn baby from being poisoned too.