A global index is similar to a partitioned table: depending on a criteria, multiple index-partititions are created each of which is its own index.
The following example creates a global index on a non-partitioned table.
create table tq84_tab (
nm number,
tx varchar2(10),
val number
);
create index tq84_ix
on tq84_tab (nm, tx)
global partition by range(nm)
(
partition lt_1e6 values less than ( 100000),
partition lt_2e6 values less than ( 200000),
partition lt_3e6 values less than ( 300000),
partition lt_4e6 values less than ( 400000),
partition lt_5e6 values less than ( 500000),
partition lt_inf values less than ( maxvalue)
)
;
drop table tq84_tab;