Dioka (a.k.a Oka-ichi), the fourth son of Dunu who lived in Oke-Ofia (in the present day Dunukofia) was the progenitor of the present day Umudioka (children of Dioka). The man Dioka chose Igbu Ichi (facial scarification) as his occupation. 

Facial Scarification was a traditional facial mark of ritual that identifies lieutenants (Spiritual Priests or Ndi Nri) of Eze Nri. While the eze Nri lived relatively secluded from his followers, he employed a group of officials called ndi Nri. These were ritual specialists, easily identifiable by facial scarifications or ichi, who traveled with ritual staffs of peace in order to purify the earth from human crimes. The ndi Nri exercised authority over wide areas of Igboland and had the power to install the next eze Nri.

Areas under Nri influence, called Odinani Nri, were open to Ndi Nri traveling within them to perform rituals and ensure bountiful harvest or restore harmony in local affairs. Local men within the odinani Nri could represent the eze Nri and share his moral authority by purchasing a series of ranked titles called Ozo and Nze. Men with these titles were known as mbùríchi and became an extension of the Nri's religio-political system. They controlled the means for agriculture and determined guilt or innocence in disputes.

Both the Ndi Nri priests and mbùríchi nobility belonged to the Ikénga, the right hand. The Ìkénga god was one dedicated to achievement and power, both of which were associated with the right hand. Expansion of the kingdom of Nri was achieved by sending mbùríchi, or converts, to other settlements.

Dunu was among Nri's Spiritual Priests (Ndi Nri) who settled at Oke-Ofia. When he wanted to settle Dioka, he asked his son what he cherished alot and he (Dioka) took a knife from Nnachi and demonstrated it on the bark of a tree which shows that he's passionate about Facial Scarification (Igbu Ichi, although this didn't mean that he abandoned other things like hunting, farming entirely).

However, the "Mma Nka", was formed and given to him (a sharp knife-like object used in the scarification). As a result, in the whole of Igboland, Oka-Ichi and subsequently  his children were the only people that had the "mma nka", hence, they're only people that gave the "ichi mark" in the whole of Igboland. 

However, it should be noted that "Igbu ichi" was entirely different from what we all know as tribal mark. Dioka and his children (Umudioka) were great travellers likewise the people of Awka (Known as Blacksmiths).

Umudioka people are widely known as the cultural ambassadors of the Igbo land. A group fierce in warfare and well reputed mercenaries. furthermore, It is taboo to sell the Dioka into slavery. Meanwhile, Umudioka people may trade slaves.

They teach and spread the Igbo customary rules in their sojourns and are semi normadic. They are the earliest judges called the Nze. They are the curators of the practices of the Nze na Ozo and initiate Igbos through the Ichi scarifications ritual as far back as 8th century AD. 

The most widely spread and largest Igbo intra ethnic group in Igboland is the Umudioka. Their settlements are well enumerated and many are established kingdoms and autonomous communities

Igbu Ichi (Facial Scarification):
Igbu ichi is an ancient practice of ritual scarification amongst the Igbo ethnic group done primarily on the forehead to the temples or from forehead to chin.

The lines of the Ichi marks represents the rays of the sun and by extension divinity. In ancient igbo cosmology the Sun "anyanwu" as it's name implies the "eye of rays" is believed to be a window through which the divine rays of Chi (God) hits the earth, ibochi is the beginning of a new day.

 the sun is seen as a gate into divinity/the divine world and thus its rays symbolized the divine. However, the vitality of ones Igboland were attracted to this very element of sun worship.

Little surprise that the igbo word for daylight is chi and day time as ubochi the rays represents the energy or spirit force from Chi, while night time is Ujichi.

However, to embark on this ritual scarification. There's first process in the divinization of a title seeker, that is to say title taking from ancient days in igbo land began with ichi scarification.

Divinization is the process of taking on the qualities, spirituality and purity of Chi, in which the living being becomes a spirit amongst men, that is the origin of the term i-chi. Meanwhile, ichi echichi refers to title taking, title taking in Igbo land was not political but a spiritual journey.

Ichi scarification was the first step in every title taking process in igbo land, it was a test of endurance, a path of pain to emerge later as a walking spirit. 

Ichi scarification was a painful process. Many times they went into sepsis or haemorrhage and died thus to survive the 14 days healing process and reemerge was a dying to oneself and re-emerging a spirit-man. Men who undergo scarification and proceed through all the rituals of title taking to the highest level (ichizu mmuo) are known as Ndiichie (living ancestors).

When the Dioka is carrying out the scarification of an initiate, Nwa Ichi (person to be tattooed), lay on a mat with face up, the Nwa Dioka (the person who draws the tattoo), from his bag, uses a sharp object (called Mmanka) to make the mark, while his wife feeds him with dry fish as he is held on the legs and hands, so as to not over power the Nwa Dioka. He douses his face with a potent substance from the Ichi leaf that is used as the local anasthesia or pain killer. He distracts the initiate with his poetry called the Abuokri which often is a traditional poem to keep him from paying attention to the scarification rites which is painful.

They were the earliest known poets . Poetry is referred to as Abuokri. A poet is referred to as Diokri or Diabuokri . It is rich in praise singing, allusions and imageries and often recited like rythmic incantations. The Oja flute is used as an accompaniment. Nowadays, Nwa Ichi is usually given a yam and a cock after the ritual of facial marking. 

In the ancient days, Nwa Dioka is usually identified with facial scarification (Igbu ichi). Meanwhile, Ichi marks were not only done on the human face it is as well done on the faces of Sculptures (effigies), Arusi and on doors or household potteries as this is because of the symbolism of the rays. It is a "Holy Mark" in Igbo land.

Short Notes:
a. Ichi scarification is performed by the Nwa-Dioka who was assisted by

b. Nwa-Nso (carries the bag of the sacred knives) and 

c. Nwa-Mgbado Ichi (holds the initiate in position) 

d. Nwa-Ichi is the one who receives the facial scarification

Descendants of Dioka are are known fierce warriors and mercenaries like people of Ohafia. Umu-Dioka forcefully penetrated all parts of Igbo Kingdom and create strong settlements and most of which are presently autonomous communities. They're known for their wise, smart and cunny mentality.

After the creation of Nigeria in 1914, Umudioka people were noted to have had strong settlements in South and Eastern parts of Nigeria. They're stated below.

1. Dioka, one of the sons of Dunu (Son of "Nwa" Okofia) are the present day Dunukofia, a Local Government in Anambra State, Nigeria. Umudioka Town in Dunukofia still answer Oka N' Ichi.

2. Umudioka village in Neni (Umudioka Ezenu), Anambra State. It was a man from Ngoka family from Ugwu village, Umudioka that migrated to Neni.

3. Umudioka village in Awka (Ajajaja Awka), Anambra State. They settled at Awka as a result of Ije osu.

4. Umudioka Orlu (Ije Osu), Imo State.  It was born out of ije osu business.

5. Umudioka village Awkuzu, Anambra State. They originated from Umuezechua village, Umudioka Dunukofia.

6. Umudioka village Okija, Anambra State.

7. Umudioka Nzam Town, Anambra West LGA, Anambra State.

8. Umudioka village Achalla, Anambra State.

9. Umudioka Obote (Ngwaland in Abia state).

10. Umudioka in Ikwerre LGA, Rivers State.

11. Asa Umudioka" in Osisioma, Abia State.

12. Umudioha in Ezeagu LGA Enugwu state

13. Dioka in Nzerem Ehime Mbano

14. Umudioka in Amaigbo in the Imo State.

15. Umudioga, Emuoha, Rivers State.

16. Orlu local Government Area Imo State, they have three traditional kingdoms - Owerre Umudioka, Umudioka Ukwu and Umudioka Ancient Kingdom.

17. Umudioka in Amiri, Nkanu West LGA, Enugu State.

18. Umudioka in Ojoto Town, Anambra State.

19.  Umudioka in Cross River

20. Umudioka in Delta State 

All this Umudioka communities listed above are connected to one ancestor which is Dioka one of the sons of Dunu nwa Okofia, today situated in Dunukofia LGA of Anambra state.